RESUMEN
Deficits in oral reading fluency (ORF) impair reading comprehension and tend to persevere throughout schooling. Therefore, the assessment and monitoring of the students' performance in ORF across time should be routinely performed to guide the instruction and intervention. The goal of this work was to develop and validate a test of ORF for Portuguese students from grades 1 to 6 (TAF - Teste de Avaliação da Fluência) that includes specific test forms for each grade level with equated scores that allow comparison across multiple assessment points. In study 1 (N = 1166), the chained equipercentile equating method was performed to equate the test forms' scores horizontally and vertically. The tests of differences performed using the equated scores indicated that they were similar within the same grade level but increased significantly across grade levels. In study 2 (N = 549), reliability and validity evidence for the test forms was collected. Test-retest correlations were higher than .90, suggesting a high stability of the scores. Significant correlations between the TAF scores and the ones obtained in other reading tests, teachers' judgments, and school outcomes, were obtained, thus providing evidence of validity for the developed test forms. This instrument allows not only interindividual comparisons but also the assessment of intra-individual changes in ORF across time or as a result of intervention programs, while avoiding learning effects that arise when the same measure is administered multiple times.