This study reports the level of participation of parents in a parent-targeted school-based drug prevention program, the differences between students whose parents participate and those who don't, and the implications for involving parents in future drug prevention programs. Among 1761 eligible seventh grade families, 1263 students (72%) and 1142 parents (65%) completed surveys assessing the quality of parent-child relationships as well as tobacco and alcohol use. Ten percent of eligible families attended at least one of the evening sessions. Compared to students whose parents completed the survey, students whose parents did not complete a survey were more likely to report they used tobacco, had more friends who used substances, were monitored less by their parents, had more risk-taking behaviors, had lower grade-point averages, and their parents had higher rates of tobacco and alcohol use. Parents who attended evening sessions had the lowest rates of tobacco use and reported spending the most time with their children. Parent-targeted drug preventions programs may stigmatize attending parents and may be unlikely to attract the highest risk families.