OBJECTIVE This research aims to understand the circumstances associated with school dropout in a cohort of Puerto Rican adolescents. METHODS The study collected data from adolescents and their parents. Information related to school dropout among adolescents was obtained from the second year follow-up data from the longitudinal study funded by NIDA "Risky Families Embedded in Risky Environments" (Grant No. R01 DA 15301). Data was collected employing a self-administered and a face-to-face interview protocol. Prediction of school dropout was assessed throughout adolescent characteristics, family background, school experiences and behaviors. RESULTS During the second follow-up, two years after the baseline assessment, approximately 6.2% of the adolescents reported dropping out from school. Logistic regression analysis indicates that older adolescents (OR = 6.6, 1.37-31.67), whose mother used drugs during pregnancy (OR = 4.9, 1.31-17.91), who reported high rates of absenteeism (OR = 4.8, 1.63-14.13), high school grade retention (OR = 3.7, 1.14-12.05), and attended school where teachers were attacked or wounded by students (O R =7.0, 1.44-34.17) were more likely to dropout of school. DISCUSSION : These findings emphasize the need to further understand the effects of different elements of adolescents' environment such as family and school. It has been posited that dropping out of school is a process whose characteristics can be detected long before it occurs. The fact that students who dropout are more likely to report skip classes and grade retention can be relevant elements in prevention and early intervention for teachers and other school personnel.