Using data from a larger intervention study of youth at risk for substance abuse, this study examined the impact of school transition on middle school and high school youth at high risk for alcohol and other drug abuse. Subjects for the larger study were 279 students from 30 secondary schools; approximately 10 students from each school were identified as high risk for substance abuse and participated in the intervention program. Data were collected three times: in the fall and spring of 1987, and in the spring of 1988. Between the 1987 and 1988 assessments, 46 youths transitioned from middle school to high school, i.e., from eighth to ninth grade. Of these students, 30 changed schools and 16 remained in the same secondary school. School transition effects were examined by comparing the group of students who changed schools between eighth and ninth grade with the group of same-aged students who did not change schools. Assessments for the intervention study included measures of behavioral coping skills; self-reports of behavior, attitudes, and substance abuse; grades and school attendance; and teacher ratings of behavior. Analysis revealed no significant differences between the school transition group and the chronologically similar comparison group. Subjects' participation in the intervention program prior to school transition may have had some preventive utility relative to school transition. (MM)