The short- and longer-term effects of brief behavioral parent training versus care as usual in children with behavioral difficulties: study protocol for a randomized controlled trial.

BACKGROUND: The access to and uptake of evidence-based behavioral parent training for children with behavioral difficulties (i.e., oppositional, defiant, aggressive, hyperactive, impulsive, and inattentive behavior) are currently limited because of a scarcity of certified therapists and long waiting lists. These problems are in part due to the long and sometimes perceived as rigid nature of most evidence-based programs and result in few families starting behavioral parent training and high dropout rates. Brief and individually tailored parenting interventions may reduce these problems and make behavioral parent training more accessible. This protocol paper describes a two-arm, multi-center, randomized controlled trial on the short- and longer-term effectiveness and cost-effectiveness of a brief, individually tailored behavioral parent training program for children with behavioral difficulties. METHODS: Parents of children aged 2-12 years referred to a child mental healthcare center are randomized to (i) three sessions of behavioral parent training with optional booster sessions or (ii) care as usual. To evaluate effectiveness, our primary outcome is the mean severity of five daily ratings by parents of four selected behavioral difficulties. Secondary outcomes include measures of parent and child behavior, well-being, and parent-child interaction. We explore whether child and parent characteristics moderate intervention effects. To evaluate cost-effectiveness, the use and costs of mental healthcare and utilities are measured. Finally, parents' and therapists' satisfaction with the brief program are explored. Measurements take place at baseline (T0), one week after the brief parent training, or eight weeks after baseline (in case of care as usual) (T1), and six months (T2) and twelve months (T3) after T1. DISCUSSION: The results of this trial could have meaningful societal implications for children with behavioral difficulties and their parents. If we find the brief behavioral parent training to be more (cost-)effective than care as usual, it could be used in clinical practice to make parent training more accessible. TRIAL REGISTRATION: The trial is prospectively registered at ClinicalTrials.gov (NCT05591820) on October 24th, 2022 and updated throughout the trial.

DNA methylation variation after a parenting program for child conduct problems: Findings from a randomized controlled trial.

This study investigated associations of the Incredible Years (IY) parenting program with children's DNA methylation. Participants were 289 Dutch children aged 3-9 years (75% European ancestry, 48% female) with above-average conduct problems. Saliva was collected 2.5 years after families were randomized to IY or care as usual (CAU). Using an intention-to-treat approach, confirmatory multiple-regression analyses revealed no significant differences between the IY and CAU groups in children's methylation levels at the NR3C1 and FKBP5 genes. However, exploratory epigenome-wide analyses revealed nine differentially methylated regions between groups, coinciding with SLAMF1, MITF, FAM200B, PSD3, SNX31, and CELSR1. The study provides preliminary evidence for associations of IY with children's salivary methylation levels and highlights the need for further research into biological outcomes of parenting programs.

Research review: Effects of parenting programs for children's conduct problems on children's emotional problems - a network meta-analysis.

BACKGROUND: Specific programs are often implemented for specific child mental health problems, while many children suffer from comorbid problems. Ideally, programs reduce a wider range of mental health problems. The present study tested whether parenting programs for children's conduct problems, and which individual and clusters of program elements, have additional effects on children's emotional problems. METHODS: We updated the search of a previous systematic review in 11 databases (e.g., PsycINFO and MEDLINE) and included studies published until July 2020 with keywords relating to 'parenting', 'program', and 'child behavioral problems'. Also, we searched for recent trials in four trial registries and contacted protocol authors. Studies were eligible for inclusion if they used a randomized controlled trial to evaluate the effects of a parenting program for children aged 2-10 years which was based on social learning theory and included a measure of children's emotional problems postintervention. RESULTS: We identified 69 eligible trials (159 effect sizes; 6,240 families). Robust variance estimation showed that parenting programs had small significant parent-reported additional effects on emotional problems immediately postintervention (Cohen's d = -0.14; 95% CI, -0.21, -0.07), but these effects faded over time. Teachers and children did not report significant effects. Additional effects on emotional problems were larger in samples with clinical baseline levels of such problems. No individual program elements predicted larger additional effects. Of the clusters of elements, combining behavior management and relationship enhancement elements was most likely to yield the strongest additional effects. CONCLUSIONS: The additional effects on emotional problems of parenting programs designed to reduce conduct problems are limited, but some clusters of elements predict larger effects. Our findings may contribute to realistic expectations of the benefits of parenting programs for children's conduct problems and inform the development of programs with wider benefits across mental health problems.

Commentary: Why treatment is the best choice for childhood mental disorders - a commentary on Roest et al. (2022).

An important question in mental healthcare for children is whether treatments are effective and safe in the long run. Here, we comment on a recent editorial perspective by Roest et al. (2022), who argue, based on an overview of systematic reviews, 'that there is no convincing evidence that interventions for the most common childhood disorders are beneficial in the long term'. We believe that the available evidence does not justify this conclusion and express our concern regarding the harmful effects of their message. We show that there is evidence to suggest beneficial longer term treatment effects for each of the disorders and explain why evidence-based treatment should be offered to children with mental disorders.

Strengthening parental self-efficacy and resilience: A within-subject experimental study with refugee parents of adolescents.

Post-migration stress and parenting adolescents can reduce parental self-efficacy. This study tested the effects of strengthening parental self-efficacy in refugee parents of adolescents and whether this makes parental self-efficacy less impacted by post-migration stressors. Using a within-subject experimental design, experience sampling data were collected in 2019 from 53 refugee parents of adolescents (Mage  = 39.7, SDage  = 5.59, 73% Syrian, 70% mothers) in the Netherlands. Data were analyzed by dynamic structural equation modeling using interrupted time-series analysis. The single-session personalized intervention strengthened parental self-efficacy (small effect: between case standardized mean difference = 0.09) and made refugee parents less vulnerable to post-migration stressors. Findings suggest that parental self-efficacy is malleable and strengthening it fosters refugee parents' resilience. Replications with longer-term follow-ups are needed.

When Is It Time to Revise or Adapt Our Prevention Programs? Introduction to Special Issue on Using Baseline Target Moderation to Assess Variation in Prevention Impact.

Adaptation of preventive interventions to increase their impact can be advanced by identifying subgroups or specific contexts where program effects appear stronger or weaker. But how do we know where to look for effect heterogeneity in ways that will inform successful adaptation? This paper introduces a special issue that brings together research across prevention science sub-disciplines that adopted baseline target moderated mediation (BTMM) designs to search for effect heterogeneity and guide adaptation of established prevention programs. For this special issue intervention  scientists analyzed data from randomized trials using BTM and BTMM models, evaluating evidence for variation in intervention impact for trials spanning different health outcomes, different developmental periods, and different social units. This introduction provides a brief summary of the various patterns of effect reported in these papers, noting that the most common pattern involved compensatory effects (those beginning the trial with greater risk or fewer protective factors benefit the most), but other patterns including rich-get-richer and partially iatrogenic effects were also detected. This paper ends with a discussion of methodological and substantive implications of these findings for future prevention research, including next-generation prevention trials.

Exploring Parenting Profiles to Understand Who Benefits from the Incredible Years Parenting Program.

Behavioral parenting programs are a theory-driven and evidence-based approach for reducing disruptive child behavior. Although these programs are effective on average, they are not equally effective in all families. Decades of moderation research has yielded very few consistent moderators, and we therefore still have little knowledge of who benefits from these programs and little understanding why some families benefit more than others. This study applied a baseline target moderation model to a parenting program, by (1) identifying parenting profiles at baseline, (2) exploring their correlations with other family characteristics and their stability, and (3) assessing whether they moderate intervention effects on child behavior. Individual participant data from four Dutch studies on the Incredible Years (IY) parenting program were used (N = 785 caregiver-child dyads). Children (58.2% boys) were at risk of disruptive behavior problems and aged between 2 and 11 years of age (M = 5.85 years; SD = 1.59). Latent profile analyses indicated three distinct baseline parenting profiles, which we labeled as follows: Low Involvement (81.4%), High Involvement (8.4%), and Harsh Parenting (10.1%). The profiles caregivers were allocated to were associated with their education, minority status, being a single caregiver, and the severity of disruptive child behavior. We found neither evidence that baseline parenting profiles changed due to participation in IY nor evidence that the profiles predicted program effects on child behavior. Our findings do not support the baseline target moderation hypothesis but raise new questions on how parenting programs may work similarly or differently for different families.

Does Social and Economic Disadvantage Predict Lower Engagement with Parenting Interventions? An Integrative Analysis Using Individual Participant Data.

There is a social gradient to the determinants of health; low socioeconomic status (SES) has been linked to reduced educational attainment and employment prospects, which in turn affect physical and mental wellbeing. One goal of preventive interventions, such as parenting programs, is to reduce these health inequalities by supporting families with difficulties that are often patterned by SES. Despite these intentions, a recent individual participant data (IPD) meta-analysis of the Incredible Years (IY) parenting program found no evidence for differential benefit by socioeconomic disadvantage (Gardner et al. in Public Health Resesearch 5, 1-144, 2017). However, it did not examine whether this was influenced by engagement in the intervention. Using intervention arm data from this pooled dataset (13 trials; N = 1078), we examined whether there was an SES gradient to intervention attendance (an indicator of engagement). We ran mixed-effects Poisson regression models to estimate incidence rate ratios (IRRs) for program attendance for each of five (binary) markers of SES: low income; unemployment; low education status; teen parent; and lone parent status. The multilevel structure of the data allowed for comparison of within-trial and between-trial effects, including tests for contextual effects. We found evidence that low SES was associated with reduced attendance at parenting programs-an 8-19% reduction depending on the SES marker. However, there was no evidence that this association is impacted by differences in SES composition between trials or by the attendance levels of higher-SES families. The findings underscore the importance of developing and prioritizing strategies that enable engagement in parenting interventions and encourage program attendance by low-SES families.

Research Review: The most effective parenting program content for disruptive child behavior - a network meta-analysis.

BACKGROUND: Programs to support parents are the recommended strategy to reduce disruptive child behavior problems. Efforts have been made to demonstrate which program components (i.e., clusters of techniques taught) increase program effects, but these methods fail to account for the fact that components rarely operate in isolation. We examine how combinations of components cluster together to form program types and use network meta-analysis to estimate the relative effects of these program types. METHODS: We updated an existing systematic review of parenting programs for disruptive child behavior and identified 197 randomized trials. We modeled clusters of components in each trial arm and chose the best-fitting model. We subsequently took 20 draws from the probability distribution of the latent class for each arm, entered each draw into a network meta-analysis model and combined findings using Rubin's rules. Combined estimates were bootstrapped to rank the clusters. We estimated main models and separate models for prevention and treatment settings. RESULTS: A five-class solution fit the data best: (1) behavior management; (2) behavior management with parental self-management; (3) behavior management with psychoeducation and relationship enhancement; (4) maximal component loading and (5) no/minimal component loading (i.e. control). In the main model and in treatment settings, all four program types were effective compared to no/minimal components. In prevention settings, only behavior management and behavior management with parental self-management were effective compared to no/minimal components. Probabilistic ranking showed that overall and in treatment settings, behavior management had the largest chance, and in prevention settings, behavior management with self-management had the largest chance, of being most effective compared to no/minimal components. CONCLUSIONS: Programs with more focused content seem more likely to yield stronger effects, and different foci may be needed in treatment versus prevention settings. Next steps include identifying individual family differences in optimal program content.

Parenting in times of refuge: A qualitative investigation.

This qualitative study sheds light on how the different phases of refuge and resettlement shape parents' perceptions of their parenting. We used in-depth interviews to examine parents' accounts of how war and refuge gave rise to different stressors, and how these in turn shaped parenting. We interviewed 27 Syrian refugee parents recently settled in the Netherlands (16 families) twice, using a grounded theory approach. We distinguished five phases of refuge, namely prewar, war, flight, displacement, and resettlement. During flight and displacement, stressors associated with financial and material losses appeared to induce parental empathy for children's suffering, which seemed to increase parental leniency. Stressors emerging from family separation during displacement, however, were reported to burden parents and to lead to uncertainty, which seemed to compromise parental warmth and sensitive discipline. While narratives suggest that families reacted in similar ways during the phases of war, flight, and displacement, differences seemed to emerge during the resettlement phase. Some parents stated that in resettlement, they experienced post-traumatic growth (e.g., increased compassion for their children) and were more autonomy supporting than before the war. Other parents seemed to struggle with accepting and supporting their children's emotions and appeared to resort more readily to parental control. Our findings suggest that emotional exhaustion plays a key role in how parents viewed their parenting changed during refuge, and that individual differences in parents' abilities to recover from emotional exhaustion played a key role in shaping parenting in resettlement.

Este estudio cualitativo aclara cómo las distintas fases del asilo y el reasentamiento determinan las percepciones de los padres con respecto a la crianza de sus hijos. Utilizamos entrevistas detalladas para analizar las explicaciones de los padres de cómo la guerra y el asilo provocaron diferentes factores desencadenantes de estrés, y de cómo estos a su vez moldearon la crianza. Entrevistamos a 27 padres refugiados sirios asentados recientemente en los Países Bajos (16 familias) dos veces utilizando un enfoque de teoría fundamentada. Distinguimos cinco fases del asilo, por ejemplo, la preguerra, la guerra, la huida, el desplazamiento y el reasentamiento. Durante la huida y el desplazamiento, los factores desencadenantes de estrés asociados con las pérdidas económicas y materiales aparentemente provocaron empatía en los padres por el sufrimiento de los niños, lo cual pareció aumentar la indulgencia de los padres. Sin embargo, se informó que los factores desencadenantes de estrés que surgieron por la separación de la familia durante el desplazamiento agobiaron a los padres y condujeron a la incertidumbre, lo cual aparentemente comprometió la amabilidad de los padres y la disciplina sensible. Si bien las historias sugieren que las familias reaccionaron de maneras similares durante las fases de la guerra, la huida y el desplazamiento, parecieron surgir diferencias durante la fase del reasentamiento. Algunos padres declararon que en el reasentamiento vivieron un crecimiento postraumático (p. ej.: una mayor compasión por sus hijos) y que fomentaron más la autonomía que antes de la guerra. A otros padres les costó aceptar y apoyar las emociones de sus hijos, y recurrieron más fácilmente al control parental. Nuestros resultados sugieren que el agotamiento emocional juega un papel fundamental en cómo los padres observaron un cambio en la crianza durante el asilo, y que las diferencias individuales en las habilidades de los padres para recuperarse del agotamiento emocional jugaron un papel clave a la hora de determinar la crianza en el reasentamiento.

Longer-Term Outcomes of the Incredible Years Parenting Intervention.

Conduct problems can develop into behavior disorders and put children at risk for other mental health problems. Parenting interventions have been shown to successfully reduce conduct problems and are often expected to prevent the development of broader mental health problems. Few studies have evaluated the longer-term and broader effects of these interventions. To what extent are parenting intervention effects sustained in the years after the intervention? And do effects pertain to conduct problems specifically, or do they also affect broader aspects of children's mental health? We used a randomized controlled trial to assess the longer-term (2.5 years) effects of the Incredible Years parenting intervention on children's conduct problems in an indicated prevention setting (N = 387; 79% retention rate). Using a multi-method (survey and computerized tasks) and multi-informant (parents, teachers, and children) approach, we tested whether initial effects on conduct problems were sustained, and whether Incredible Years had broader effects on children's peer problems, emotional problems, attention-deficit/hyperactivity disorder (ADHD) symptoms, attention and inhibition deficits, and service use. Incredible Years, relative to control (no intervention), led to sustained reductions in parent-reported conduct problems (Cohen's d = 0.31), but not teacher- and child-reported conduct problems. There were no broader benefits: Incredible Years did not reduce children's peer problems, emotional problems, ADHD-symptoms, attention and inhibition deficits, or their service use. Improvements in parents' perceptions of child conduct problems sustained until 2.5 years later. Our findings do not show benefits of Incredible Years as a preventive intervention for children's broader mental health.

Strengthening a Culture of Prevention in Low- and Middle-Income Countries: Balancing Scientific Expectations and Contextual Realities.

Relevant initiatives are being implemented in low- and middle-income countries (LMICs) aimed at strengthening a culture of prevention. However, cumulative contextual factors constitute significant barriers for implementing rigorous prevention science in these contexts, as defined by guidelines from high-income countries (HICs). Specifically, disseminating a culture of prevention in LMICs can be impacted by political instability, limited health coverage, insecurity, limited rule of law, and scarcity of specialized professionals. This manuscript offers a contribution focused on strengthening a culture of prevention in LMICs. Specifically, four case studies are presented illustrating the gradual development of contrasting prevention initiatives in northern and central Mexico, Panamá, and Sub-Saharan Africa. The initiatives share the common goal of strengthening a culture of prevention in LMICs through the dissemination of efficacious parenting programs, aimed at reducing child maltreatment and improving parental and child mental health. Together, these initiatives illustrate the following: (a) the relevance of adopting a definition of culture of prevention characterized by national commitments with expected shared contributions by governments and civil society, (b) the need to carefully consider the impact of context when promoting prevention initiatives in LMICs, (c) the iterative, non-linear, and multi-faceted nature of promoting a culture of prevention in LMICs, and (d) the importance of committing to cultural competence and shared leadership with local communities for the advancement of prevention science in LMICs. Implications for expanding a culture of prevention in LMICs are discussed.

Study protocol: randomized controlled trial of manualized components in home visitation to reduce mothers' risk for child maltreatment.

BACKGROUND: This study tests whether home visitation to prevent child maltreatment can be improved by adding manualized program components, targeting four key risk factors for child maltreatment: low parental self-efficacy, high levels of perceived stress, parental anger, and post-traumatic stress symptoms. Home visitation is widely implemented, but effects on child maltreatment risk tend to be modest at best. Home visitation tends to be rather flexible (i.e., professionals decide how to support each family). We will test whether adding manualized program components increases program effectiveness, by ensuring that key risk factors are addressed, while maintaining flexibility. In addition, we will test whether any component effects on reduced child maltreatment risk can be explained (i.e., is mediated) by ameliorated risk factors. Lastly, we will test whether the components are more effective for some mothers (e.g., those at highest child maltreatment risk) than for others. METHODS: We will conduct a randomized controlled trial among 398 mothers enrolled in a Dutch home visiting program targeting families at risk for child maltreatment. Mothers in the experimental group will receive the manualized components in two consecutive home visits, while mothers in the control group will receive regular home visits (care as usual). Mothers will fill out questionnaires at four time points: before and after each of the two home visits. Outcome variables include the four targeted risk factors parental self-efficacy, perceived stress, parental anger, and (recognition of) post-traumatic stress symptoms, as well as parenting practices (e.g., rejection and affection), and risk for child maltreatment. DISCUSSION: This study aims to determine whether adding manualized program components to a flexible home visiting program increases program effectiveness on risk for child maltreatment. In addition, our test of whether the effects of the components on risk for child maltreatment is explained (i.e., mediated) by amelioration of the targeted risk factors, may contribute to our understanding of the role of these risk factors in child maltreatment. Our tests of which mothers benefit most from adding the components may help move the field towards evidence-based personalized family support. TRIAL REGISTRATION: This trial has been retrospectively registered in the Netherlands Trial Register (NL8005).

Online parent programs for children's behavioral problems: a meta-analytic review.

A recent increase in the development of online parent programs calls for the need to understand how effective these strategies are for improving children's mental health. We meta-analyzed the effects of online parent programs on children's behavioral problems. Moreover, we explored the combinations of program components to yield stronger program effects. Medline, PsycINFO, Web of Science, and the Cochrane Library were searched. We included peer-reviewed randomized studies evaluating the effect of an online parent program. Effect sizes (Hedges' g) were calculated from post intervention means and standard deviations. We used Qualitative Comparative Analysis (QCA) to identify pathways to effectiveness and individual content and delivery components that seem sufficient or necessary for yielding high effectiveness. Of 2941 articles, 12 articles with a total of 2025 participants met the inclusion criteria. Online parent programs have significant effects on children's behavioral problems (g = - 0.32; 95% CI, - 0.47 to - 0.17), emotional problems (g = - 0.22; 95% CI, - 0.31 to - 0.13), and parental mental health problems (g = - 0.30; 95% CI, - 0.42 to - 0.17). In the QCA, sending parents reminders to work on the program was the only one sufficient component. In conclusion, online support programs reduce children's behavioral and emotional problems and improve parental mental health. Sending parents reminders to work on the program seems to contribute to high effectiveness. Review Registration This study was registered with PROSPERO, number CRD42017080051.

The Earlier the Better? Individual Participant Data and Traditional Meta-analysis of Age Effects of Parenting Interventions.

Strong arguments have been made for early intervention for child problems, stating that early is more effective than later, as the brain is more malleable, and costs are lower. However, there is scant evidence from trials to support this hypothesis, which we therefore tested in two well-powered, state-of-the-art meta-analyses with complementary strengths: (a) Individual participant data (IPD) meta-analysis of European trials of Incredible Years parenting intervention (k = 13, n = 1696; age = 2-11); (b) Larger, trial-level robust variance estimation meta-analysis of a wider range of parenting programs (k = 156, n = 13,378, Mage  = 2-10) for reducing disruptive behavior. Both analyses found no evidence that intervention earlier in childhood was more effective; programs targeted at a narrower age range were no more effective than general ones.

Co-occurring change in children's conduct problems and maternal depression: Latent class individual participant data meta-analysis of the Incredible Years parenting program.

Children vary in the extent to which they benefit from parenting programs for conduct problems. How does parental mental health change if children benefit less or more? We assessed whether changes in conduct problems and maternal depressive symptoms co-occur following participation in the Incredible Years parenting program. We integrated individual participant data from 10 randomized trials (N = 1280; children aged 2-10 years) and distinguished latent classes based on families' baseline and post-test conduct problems and maternal depressive symptoms, using repeated measures latent class analysis (RMLCA) and latent transition analysis (LTA). Classes differed mainly in severity of conduct problems and depression (RMLCA; 4 classes). Conduct problems reduced in all classes. Depressive symptoms did not change in most classes, except in a class of families where conduct problems and depression were particularly severe. Incredible Years led to a greater likelihood of families with particularly severe conduct problems and depression moving to a class with mild problems (LTA; 3 classes). Our findings suggest that for the majority of families, children's conduct problems reduce, but maternal depressive symptoms do not, suggesting relative independence, with the exception of families with severe depression and severe conduct problems where changes for the better do co-occur.

Research Review: Harnessing the power of individual participant data in a meta-analysis of the benefits and harms of the Incredible Years parenting program.

BACKGROUND: Parenting programs aim to reduce children's conduct problems through improvement of family dynamics. To date, research on the precise benefits and possible harms of parenting programs on family well-being has been unsystematic and likely to be subject to selective outcome reporting and publication bias. Better understanding of program benefits and harms requires full disclosure by researchers of all included measures, and large enough numbers of participants to be able to detect small effects and estimate them precisely. METHODS: We obtained individual participant data for 14 of 15 randomized controlled trials on the Incredible Years parenting program in Europe (total N = 1,799). We used multilevel modeling to estimate program effects on 13 parent-reported outcomes, including parenting practices, children's mental health, and parental mental health. RESULTS: Parental use of praise, corporal punishment, threats, and shouting improved, while parental use of tangible rewards, monitoring, or laxness did not. Children's conduct problems and attention deficit hyperactivity disorder (ADHD) symptoms improved, while emotional problems did not. Parental mental health (depressive symptoms, self-efficacy, and stress) did not improve. There was no evidence of harmful effects. CONCLUSIONS: The Incredible Years parenting program improves the aspects of family well-being that it is primarily designed to improve: parenting and children's conduct problems. It also improves parent-reported ADHD symptoms in children. Wider benefits are limited: the program does not improve children's emotional problems or parental mental health. There are no signs of harm on any of the target outcomes.

Are Relationship Enhancement and Behavior Management "The Golden Couple" for Disruptive Child Behavior? Two Meta-analyses.

Parenting programs for reducing disruptive child behavior are built on two main perspectives: relationship enhancement (i.e., unconditional sensitivity diminishes disruptiveness) and behavior management (i.e., conditional rewards diminish disruptiveness). Two meta-analyses (156 and 41 RCTs; Ntotal  = 15,768; Mchildage  = 1-11 years) tested the theoretical model that integrating relationship enhancement with behavior management is superior to behavior management alone. The integrative approach showed no overall superiority. Relative to behavior management, the integrative approach was superior in treatment settings, but inferior in prevention settings (Meta-analysis 1). The integrative approach and behavior management approach did not have differential sustained effects up to 3 years after the program (Meta-analysis 2). Findings argue against current practice to implement the same parenting programs in treatment and prevention settings.

Understanding Who Benefits from Parenting Interventions for Children's Conduct Problems: an Integrative Data Analysis.

Parenting interventions are an effective strategy to reduce children's conduct problems. For some families, that is, not all families benefit equally. Individual trials tend to be underpowered and often lack variability to differentiate between families how benefit less or more. Integrating individual family level data across trials, we aimed to provide more conclusive results about often presumed key family (parental education and ethnic background) and child characteristics (problem severity, ADHD symptoms and emotional problems) as putative moderators of parenting intervention effects. We included data from 786 families (452 intervention; 334 control) from all four trials on the Incredible Years parenting intervention in The Netherlands (three randomized; one matched control). Children ranged between 2 and 10 years (M = 5.79; SD = 1.66). Of the families, 31% had a lower educational level and 29% had an ethnic minority background. Using multilevel regression, we tested whether each of the putative moderators affected intervention effects. Incredible Years reduced children's conduct problems (d = - .34). There were no differential effects by families' educational or ethnic background, or by children's level of ADHD symptoms. Children with more severe conduct problems and those with more emotional problems benefited more. Post hoc sensitivity analyses showed that for the two trials with longer-term data, moderation effects disappeared at 4 or 12 months follow-up. Often assumed moderators have some, but limited abilities to explain who benefits from parenting interventions. This suggests the need for studying theoretically more precise moderators in prevention research, other than relatively static family characteristics alone.