Lifetime years married held steady for men with a BA degree since 1960 but dropped to lowest level since 1880 for men without a BA.

Trends in life expectancy and marriage patterns work together to determine expected lifetime years married. In 1880, adult life expectancy was short and marriages were more likely to end by death than divorce. Since then, although there have been substantial life expectancy gains in adulthood, marriage has been increasingly delayed or forgone and cohabitation and divorce are far more prevalent. Whether adults today can expect to spend more or fewer years married than in the past depends on the relative magnitude of changes in mortality and marriage. We estimate trends in men's expected lifetime years married (and in other marital statuses) from 1880 to 2019 and by bachelor's degree (BA) status from 1960 to 2019. Our results show a rise in men's expected lifetime years married between 1880 and the Baby Boom era and a subsequent fall. There are large and growing differences by BA status. Men with a BA have had high and relatively stable expected lifetime years married since 1960. For men without a BA, expected lifetime years married has plummeted to lows not seen among men since 1880. Cohabitation accounts for a substantial fraction, although not all, of these declines. Our results demonstrate how increasing inequality in both life expectancy and marriage patterns combine to amplify educational differences in lifetime experiences of coresidential partnerships.

Eight Decades of Educational Assortative Mating: A Research Note.

Recent social and economic trends in the United States, including increasing economic inequality, women's growing educational advantage, and the rise of online dating, have ambiguous implications for patterns of educational homogamy. In this research note, we examine changes in educational assortative mating in the United States over the last eight decades (1940 to 2020) using the U.S. decennial censuses and the American Community Survey, extending and expanding earlier work by Schwartz and Mare. We find that the rise in educational homogamy noted by Schwartz and Mare has not continued. Increases in educational homogamy stalled around 1990 and began reversing in the 2000s. We find a growing tendency for marriages to cross educational boundaries, but a college degree remains the strongest dividing line to intermarriage. A key trend explaining this new pattern is women's increasing tendency to marry men with less education than themselves. If not for this trend, homogamy would have continued increasing until the early 2010s. We also show substantial heterogeneity by race, ethnicity, and nativity and among same- versus different-sex couples.

Changes in Couples' Earnings Following Parenthood and Trends in Family Earnings Inequality.

The growing economic similarity of spouses has contributed to rising income inequality across households. Explanations have typically centered on assortative mating, but recent work has argued that changes in women's employment and spouses' division of paid work have played a more important role. We expand this work to consider the critical turning point of parenthood in shaping couples' division of employment and earnings. Drawing on three U.S. nationally representative surveys, we examine the role of parenthood in spouses' earnings correlations between 1968 and 2015. We examine the extent to which changes in spouses' earnings correlations are due to (1) changes upon entry into marriage (assortative mating), (2) changes between marriage and parenthood, (3) changes following parenthood, and (4) changes in women's employment. Our findings show that increases in the correlation between spouses' earnings prior to 1990 came largely from changes between marriage and first birth, but increases after 1990 came almost entirely from changes following parenthood. In both instances, changes in women's employment are key to increasing earnings correlations. Changes in assortative mating played little role in either period. An assessment of the aggregate-level implications points to the growing significance of earnings similarity after parenthood for rising income inequality across families.

Opportunity and change in occupational assortative mating.

This article documents how opportunity and change in the U.S. occupational structure shaped patterns of occupational assortative mating between 1970 and 2015-2017. Trends in occupational assortative mating have often been cited as potentially contributing to the rise in economic inequality-the idea that doctors increasingly marry doctors instead of nurses-thereby exacerbating the concentration of resources among advantaged households. Previous estimates of trends in occupational assortative mating are now decades old and their impact on household inequality has not been quantified. Our results show large-scale change. The prevalence of dual-professional couples nearly tripled between 1970 and 2015-2017. Changes were especially large among particular occupational combinations. For instance, male doctors have become increasingly likely to be married to female doctors, and male lawyers to female lawyers. Almost all of the changes in occupational assortative mating patterns, however, are accounted for by changes in the distributions of spouses' occupations, for example, the rise of women in professional occupations. Because of this, the contribution of occupational assortative mating to the rise in economic inequality has been small. In the absence of any association between spouses' occupations, observed increases in household earnings inequality would have been reduced by 5%. Although this is a small portion of overall changes in inequality, it is much larger than prior estimates of the effects of educational assortative mating on inequality, which recent studies have estimated to be essentially zero.

Clinical genetics and outcome of left ventricular non-compaction cardiomyopathy.

AIMS: In this study, we aimed to clinically and genetically characterize LVNC patients and investigate the prevalence of variants in known and novel LVNC disease genes. INTRODUCTION: Left ventricular non-compaction cardiomyopathy (LVNC) is an increasingly recognized cause of heart failure, arrhythmia, thromboembolism, and sudden cardiac death. We sought here to dissect its genetic causes, phenotypic presentation and outcome. METHODS AND RESULTS: In our registry with follow-up of in the median 61 months, we analysed 95 LVNC patients (68 unrelated index patients and 27 affected relatives; definite familial LVNC = 23.5%) by cardiac phenotyping, molecular biomarkers and exome sequencing. Cardiovascular events were significantly more frequent in LVNC patients compared with an age-matched group of patients with non-ischaemic dilated cardiomyopathy (hazard ratio = 2.481, P = 0.002). Stringent genetic classification according to ACMG guidelines revealed that TTN, LMNA, and MYBPC3 are the most prevalent disease genes (13 patients are carrying a pathogenic truncating TTN variant, odds ratio = 40.7, Confidence interval = 21.6-76.6, P < 0.0001, percent spliced in 76-100%). We also identified novel candidate genes for LVNC. For RBM20, we were able to perform detailed familial, molecular and functional studies. We show that the novel variant p.R634L in the RS domain of RBM20 co-segregates with LVNC, leading to titin mis-splicing as revealed by RNA sequencing of heart tissue in mutation carriers, protein analysis, and functional splice-reporter assays. CONCLUSION: Our data demonstrate that the clinical course of symptomatic LVNC can be severe. The identified pathogenic variants and distribution of disease genes-a titin-related pathomechanism is found in every fourth patient-should be considered in genetic counselling of patients. Pathogenic variants in the nuclear proteins Lamin A/C and RBM20 were associated with worse outcome.

Enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation.

During hibernation, thirteen-lined ground squirrels (Ictidomys tridecemlineatus) regularly cycle between bouts of torpor and interbout arousal (IBA). Most of the brain is electrically quiescent during torpor but regains activity quickly upon arousal to IBA, resulting in extreme oscillations in energy demand during hibernation. We predicted increased functional capacity of brain mitochondria during hibernation compared with spring to accommodate the variable energy demands of hibernation. To address this hypothesis, we examined mitochondrial bioenergetics in the ground squirrel brain across three time points: spring (SP), torpor (TOR), and IBA. Respiration rates of isolated brain mitochondria through complex I of the electron transport chain were more than twofold higher in TOR and IBA than in SP (P < 0.05). We also found a 10% increase in membrane potential between hibernation and spring (P < 0.05), and that proton leak was lower in TOR and IBA than in SP. Finally, there was a 30% increase in calcium loading in SP brain mitochondria compared with TOR and IBA (P < 0.01). To analyze brain mitochondrial abundance between spring and hibernation, we measured the ratio of copy number in a mitochondrial gene (ND1) vs. a nuclear gene (B2M) in frozen cerebral cortex samples. No significant differences were observed in DNA copies between SP and IBA. These data show that brain mitochondrial bioenergetics are not static across the year and suggest that brain mitochondria function more effectively during the hibernation season, allowing for rapid production of energy to meet demand when extreme physiological changes are occurring.

Trends in Economic Homogamy: Changes in Assortative Mating or the Division of Labor in Marriage?

The growing economic resemblance of spouses has contributed to rising inequality by increasing the number of couples in which there are two high- or two low-earning partners. The dominant explanation for this trend is increased assortative mating. Previous research has primarily relied on cross-sectional data and thus has been unable to disentangle changes in assortative mating from changes in the division of spouses' paid labor-a potentially key mechanism given the dramatic rise in wives' labor supply. We use data from the Panel Study of Income Dynamics (PSID) to decompose the increase in the correlation between spouses' earnings and its contribution to inequality between 1970 and 2013 into parts due to (a) changes in assortative mating, and (b) changes in the division of paid labor. Contrary to what has often been assumed, the rise of economic homogamy and its contribution to inequality is largely attributable to changes in the division of paid labor rather than changes in sorting on earnings or earnings potential. Our findings indicate that the rise of economic homogamy cannot be explained by hypotheses centered on meeting and matching opportunities, and they show where in this process inequality is generated and where it is not.

Targeted Mutagenesis, Precise Gene Editing, and Site-Specific Gene Insertion in Maize Using Cas9 and Guide RNA.

Targeted mutagenesis, editing of endogenous maize (Zea mays) genes, and site-specific insertion of a trait gene using clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas)-guide RNA technology are reported in maize. DNA vectors expressing maize codon-optimized Streptococcus pyogenes Cas9 endonuclease and single guide RNAs were cointroduced with or without DNA repair templates into maize immature embryos by biolistic transformation targeting five different genomic regions: upstream of the liguleless1 (LIG1) gene, male fertility genes (Ms26 and Ms45), and acetolactate synthase (ALS) genes (ALS1 and ALS2). Mutations were subsequently identified at all sites targeted, and plants containing biallelic multiplex mutations at LIG1, Ms26, and Ms45 were recovered. Biolistic delivery of guide RNAs (as RNA molecules) directly into immature embryo cells containing preintegrated Cas9 also resulted in targeted mutations. Editing the ALS2 gene using either single-stranded oligonucleotides or double-stranded DNA vectors as repair templates yielded chlorsulfuron-resistant plants. Double-strand breaks generated by RNA-guided Cas9 endonuclease also stimulated insertion of a trait gene at a site near LIG1 by homology-directed repair. Progeny showed expected Mendelian segregation of mutations, edits, and targeted gene insertions. The examples reported in this study demonstrate the utility of Cas9-guide RNA technology as a plant genome editing tool to enhance plant breeding and crop research needed to meet growing agriculture demands of the future.

Melatonin receptor signaling contributes to neuroprotection upon arousal from torpor in thirteen-lined ground squirrels.

The brain of mammalian hibernators is naturally protected. Hibernating ground squirrels undergo rapid and extreme changes in body temperature and brain perfusion as they cycle between lengthy torpor bouts and brief periods of euthermia called interbout arousals (IBAs). Arousal from torpor to IBA occurs rapidly, but there is no evidence of brain injury accompanying this extreme physiological transition. Production of the hormone melatonin accompanies arousal, suggesting that it plays a protective role at this time. Here, we investigated mechanisms of melatonin receptor-mediated protection in the brain of the hibernating ground squirrel. We administered the competitive melatonin receptor antagonist luzindole (30 mg/kg ip) to ground squirrels at the predicted end of a torpor bout, triggering an arousal. We found that luzindole-treated animals exhibited caspase-3 activity two times higher than vehicle-treated animals in the hypothalamus at midarousal (P = 0.01), suggesting that melatonin receptor signaling is important for protection in this brain region. We also found a 30% decline in succinate-fueled mitochondrial respiration in luzindole-treated animals compared with vehicle-treated animals (P = 0.019), suggesting that melatonin receptor signaling is important for optimal mitochondrial function during arousal from torpor. The mitochondrial effects of luzindole treatment were seen only during the hibernation season, indicating that this effect is specifically important for arousal from torpor. These data provide evidence for the protective role of melatonin receptor signaling during the extreme physiological transition that occurs when a hibernating mammal arouses from torpor and provide further evidence for regional and seasonal changes in the hibernator brain.

The Reversal of the Gender Gap in Education and Trends in Marital Dissolution.

The reversal of the gender gap in education has potentially far-reaching consequences for marriage markets, family formation, and relationship outcomes. One possible consequence of this is the growing number of marriages in which wives have more education than their husbands. Previous studies have found this type of union to be at higher risk of dissolution. Using data on marriages formed between 1950 and 2004 in the United States, we evaluate whether this association has persisted as the prevalence of this relationship type has increased. Our results show a large shift in the association between spouses' relative education and marital dissolution. In particular, we confirm that marriages in which wives have the educational advantage were once more likely to dissolve, but we show that this association has disappeared in more recent marriage cohorts. Another key finding is that the relative stability of marriages between educational equals has increased. These results are consistent with a shift away from rigid gender specialization toward more flexible, egalitarian partnerships and provide an important counterpoint to claims that progress toward gender equality in heterosexual relationships has stalled.

CHANGE AND VARIATION IN U.S. COUPLES' EARNINGS EQUALITY FOLLOWING PARENTHOOD.

In the context of broad increases in gender equality and growing socioeconomic disparities along multiple dimensions of family life, we examine changes in within-family earnings equality following parenthood and the extent to which they have played out differently by education. Our analysis relies on links between rich surveys and administrative tax records that provide high quality earnings data for husbands and wives spanning two years before and up to 10 years following first births from the 1980s to the 2000s in the United States (Survey of Income and Program Participation Synthetic Beta files; N=21,300 couples and 194,100 couple-years). Accounting for time-invariant couple characteristics and year and age fixed effects, we find that wives' share of total couple earnings declines substantially after parenthood and remains lower over the observation window. Cohort changes in within-family earnings equality are modest and concentrated among the earliest cohort of parents, and data provide little evidence of differential change by education. Wives' financial dependence on their husbands increases substantially after parenthood, irrespective of education and cohort. These findings have implications for women's vulnerability, particularly in the U.S. where divorce remains common and public support for families is weak.

Prevalence of childhood mental disorders in high-income countries: a systematic review and meta-analysis to inform policymaking.

QUESTION: Mental disorders typically start in childhood and persist, causing high individual and collective burdens. To inform policymaking to address children's mental health in high-income countries we aimed to identify updated data on disorder prevalence. METHODS: We identified epidemiological studies reporting mental disorder prevalence in representative samples of children aged 18 years or younger-including a range of disorders and ages and assessing impairment (searching January 1990 through February 2021). We extracted associated service-use data where studies assessed this. We conducted meta-analyses using a random effects logistic model (using R metafor package). FINDINGS: Fourteen studies in 11 countries met inclusion criteria, published from 2003 to 2020 with a pooled sample of 61 545 children aged 4-18 years, including eight reporting service use. (All data were collected pre-COVID-19.) Overall prevalence of any childhood mental disorder was 12.7% (95% CI 10.1% to 15.9%; I2=99.1%). Significant heterogeneity pertained to diagnostic measurement and study location. Anxiety (5.2%), attention-deficit/hyperactivity (3.7%), oppositional defiant (3.3%), substance use (2.3%), conduct (1.3%) and depressive (1.3%) disorders were the most common. Among children with mental disorders, only 44.2% (95% CI 37.6% to 50.9%) received any services for these conditions. CONCLUSIONS: An estimated one in eight children have mental disorders at any given time, causing symptoms and impairment, therefore requiring treatment. Yet even in high-income countries, most children with mental disorders are not receiving services for these conditions. We discuss the implications, particularly the need to substantially increase public investments in effective interventions. We also discuss the policy urgency, given the emerging increases in childhood mental health problems since the onset of the COVID-19 pandemic (PROSPERO CRD42020157262).

Regulation of bat echolocation pulse acoustics by striatal dopamine.

The ability to control the bandwidth, amplitude and duration of echolocation pulses is a crucial aspect of echolocation performance but few details are known about the neural mechanisms underlying the control of these voice parameters in any mammal. The basal ganglia (BG) are a suite of forebrain nuclei centrally involved in sensory-motor control and are characterized by their dependence on dopamine. We hypothesized that pharmacological manipulation of brain dopamine levels could reveal how BG circuits might influence the acoustic structure of bat echolocation pulses. A single intraperitoneal injection of a low dose (5 mg kg(-1)) of the neurotoxin 1-methyl-4-phenylpyridine (MPTP), which selectively targets dopamine-producing cells of the substantia nigra, produced a rapid degradation in pulse acoustic structure and eliminated the bat's ability to make compensatory changes in pulse amplitude in response to background noise, i.e. the Lombard response. However, high-performance liquid chromatography (HPLC) measurements of striatal dopamine concentrations revealed that the main effect of MPTP was a fourfold increase rather than the predicted decrease in striatal dopamine levels. After first using autoradiographic methods to confirm the presence and location of D(1)- and D(2)-type dopamine receptors in the bat striatum, systemic injections of receptor subtype-specific agonists showed that MPTP's effects on pulse acoustics were mimicked by a D(2)-type dopamine receptor agonist (Quinpirole) but not by a D(1)-type dopamine receptor agonist (SKF82958). The results suggest that BG circuits have the capacity to influence echolocation pulse acoustics, particularly via D(2)-type dopamine receptor-mediated pathways, and may therefore represent an important mechanism for vocal control in bats.

Community and Academic Physicians Working Together in Integrated Health Care Systems.

OBJECTIVE: To examine best practices and policies for effectively merging community and academic physicians in integrated health care systems. METHODS: Deans of US allopathic medical schools were systematically interviewed between February and June 2017 regarding growth in their faculty practice plan (FPP), including logistics and best practices for integration of community physicians. RESULTS: The survey was completed by 107 of 143 (74.8) of US medical school deans approached. Of these institutions, 73 met criteria for final analysis (research-based medical schools with FPPs of >300 physicians). Most academic medical center-based FPPs have increased in size over the last 5 years, with further growth anticipated via adding community physicians (85%). Because of disparate practice locations, integration of community and academic physicians has been slow. When fully integrated, community physicians predominantly have a clinical role with productivity incentives. Deans report that cultural issues must be addressed to avoid conflict. Consensus exists that transparent clinical work requirements for all FPP members, clearly defined productivity incentives, additional promotion tracks, and early involvement of department chairs and other leaders enhances trust and creates better synergy among all physician providers. CONCLUSION: Findings from this study should help guide FPPs, academic medical center leaders, chief medical officers, and professional and trade organizations in working toward positive physician synergy in consolidated health care organizations. Work and cultural considerations must be addressed to honor distinct talents of each physician group, facilitating smooth transition from disparate groups to healthy synergy.

Perineuronal net expression in the brain of a hibernating mammal.

During hibernation, mammals like the 13-lined ground squirrel cycle between physiological extremes. Most of the hibernation season is spent in bouts of torpor, where body temperature, heart rate, and cerebral blood flow are all very low. However, the ground squirrels periodically enter into interbout arousals (IBAs), where physiological parameters return to non-hibernating levels. During torpor, neurons in many brain regions shrink and become electrically quiescent, but reconnect and regain activity during IBA. Previous work showed evidence of extracellular matrix (ECM) changes occurring in the hypothalamus during hibernation that could be associated with this plasticity. Here, we examined expression of a specialized ECM structure, the perineuronal net (PNN), in the forebrain of ground squirrels in torpor, IBA, and summer (non-hibernating). PNNs are known to restrict plasticity, and could be important for retaining essential connections in the brain during hibernation. We found PNNs in three regions of the hypothalamus: ventrolateral hypothalamus, paraventricular nucleus (PVN), and anterior hypothalamic area. We also found PNNs throughout the cerebral cortex, amygdala, and lateral septum. The total area covered by PNNs within the PVN was significantly higher during IBA compared to non-hibernating and torpor (P < 0.01). Additionally, the amount of PNN coverage area per Nissl-stained neuron in the PVN was significantly higher in hibernation compared to non-hibernating (P < 0.05). No other significant differences were found across seasons. The PVN is involved in food intake and homeostasis, and PNNs found here could be essential for retaining vital life functions during hibernation.

The Demography of Families: A Review of Patterns and Change.

The authors review demographic trends and research on families in the United States, with a special focus on the past decade. They consider the following several topics: (a) marriage and remarriage, (b) divorce, (c) cohabitation, (d) fertility, (e) same-gender unions, (f) immigrant families, and (g) children's living arrangements. Throughout, the authors review both overall trends and patterns as well as those by social class and race-ethnicity. The authors discuss major strands of recent research, emphasizing emerging themes and promising directions. They close with a summary of central patterns and trends and conclude that recent trends are not as uniform as they tended to be in earlier decades, making the description of family change increasingly complex.

Distribution of 2-[I]iodomelatonin binding in the brain of Mexican free-tailed bats (Tadarida brasiliensis).

The neurohormone melatonin is an important signal for both time of day and time of year in many seasonally breeding animals. High densities of melatonin receptors have been found in the suprachiasmatic nucleus, median eminence, and the pituitary gland in almost all mammals investigated so far, and lower densities of melatonin receptors have also been localized to other brain regions varying in a species-specific fashion. Because species-specific differences in receptor distributions have been correlated with differences in behavior and ecology, a comparative study of how melatonin receptors are distributed in vertebrate brains can be useful to the understanding of the functional organization of neural circuits controlling daily and seasonal behaviors. In this study, we localized and characterized melatonin binding sites in the brain of the Mexican free-tailed bat (Tadarida brasiliensis) using in vitro autoradiography with 2-[(125)I]iodomelatonin. Tadarida brasiliensis is a nocturnal insectivorous mammal that seasonally migrates, reproduces once a year, and exhibits documented sexual dimorphisms in seasonal reproductive behaviors, most notably in courtship vocalizations. Prominent 2-[(125)I]iodomelatonin binding was found in the median eminence, suprachiasmatic nuclei, and hippocampus, similar to that observed in other mammals. High densities of binding were also localized to structures of the basal ganglia, including the caudate nucleus, putamen, and nucleus accumbens, a feature commonly observed in songbirds but not in mammals. Saturation analysis indicated that the observed binding sites had an affinity for melatonin typical of the binding properties for the Mel(1a) receptor subtype. We conclude that melatonin receptor distributions in the Mexican free-tailed bat brain appear to show similarities with the reproductive and circadian systems of other mammals and the basal ganglia of songbirds.

Assortative matching among same-sex and different-sex couples in the United States, 1990-2000.

Same-sex couples are less likely to be homogamous than different-sex couples on a variety of characteristics including race/ethnicity, age, and education. This study confirms results from previous studies which used 1990 U.S. census data and extends previous analyses to examine changes from 1990 to 2000. We find that same-sex male cohabitors are generally the least likely to resemble one another, followed by same-sex female cohabitors, different-sex cohabitors, and different-sex married couples. Despite estimated growth in the numbers of same-sex couples in the population and the increasing acceptance of same-sex unions, we find little evidence of diminishing differences in the resemblance of same- and different-sex couples between 1990 and 2000, with the possible exception of educational homogamy.

Six decades of preventing and treating childhood anxiety disorders: a systematic review and meta-analysis to inform policy and practice.

QUESTION: Anxiety disorders are the most prevalent childhood mental disorders. They also start early and persist, causing high individual and collective costs. To inform policy and practice, we therefore asked: What is the best available research evidence on preventing and treating these disorders? METHODS: We sought randomised controlled trials (RCTs) evaluating interventions addressing anxiety problems in young people. We identified RCTs by searching CINAHL, ERIC, MEDLINE, PsycINFO and Web of Science. Thirty-three RCTs met inclusion criteria-evaluating 8 prevention programmes, 12 psychosocial treatments and 7 pharmacological treatments. We then conducted meta-analyses by intervention type. FINDINGS: For prevention, the cognitive-behavioural therapy (CBT) programme Coping and Promoting Strength stood out for reducing anxiety diagnoses. For psychosocial treatment, 9 CBT interventions also reduced diagnoses: Cool Kids; Cool Little Kids Plus Social Skills; Coping Cat; Coping Koala; One-Session Treatment; Parent Education Program; Skills for Academic and Social Success; Strongest Families and Timid to Tiger. Successful CBT interventions were used with children ranging from pre-schoolers to teens in homes, communities/schools and clinics. For pharmacological treatment, selective-serotonergic-reuptake-inhibitors (SSRIs) significantly improved symptoms. Fluoxetine stood out for also reducing post-test diagnoses, but caused adverse events. Meta-analyses indicated strongest effects for CBT (Log OR=0.95; 95% CI, 0.69 to 1.21) and SSRI treatments (1.57; 1.09 to 2.06). CONCLUSIONS: CBT is effective for preventing and treating childhood anxiety-across a range of ages and formats. Fluoxetine is also an effective treatment but side effects must be managed. CBT prevention and treatment interventions should be made widely available, adding fluoxetine in severe cases.

NEIGHBORHOOD NORMS AND SUBSTANCE USE AMONG TEENS.

This paper uses new data from the Los Angeles Family and Neighborhood Survey (L.A. FANS) to examine how neighborhood norms shape teenagers' substance use. Specifically, it takes advantage of clustered data at the neighborhood level to relate adult neighbors' attitudes and behavior with respect to smoking, drinking, and drugs, which we treat as norms, to teenagers' own smoking, drinking, and drug use. We use hierarchical linear models to account for parents' attitudes and behavior and other characteristics of individuals and families. We also investigate how the association between neighborhood norms and teen behavior depends on: (1) the strength of norms, as measured by consensus in neighbors' attitudes and conformity in their behavior; (2) the willingness and ability of neighbors to enforce norms, for instance, by monitoring teens' activities; and (3) the degree to which teens are exposed to their neighbors. We find little association between neighborhood norms and teen substance use, regardless of how we condition the relationship. We discuss possible theoretical and methodological explanations for this finding.