||BACKGROUND: This article reports the results of a 5-year, longitudinal evaluation of the effectiveness of Drug Abuse Resistance Education (DARE), a school-based primary drug prevention curriculum designed for introduction during the last year of elementary education. DARE is the most widely disseminated school-based prevention curriculum in the United States. METHOD: Twenty-three elementary schools were randomly assigned to receive DARE and 8 were designated comparison schools. Students in the DARE schools received 16 weeks of protocol-driven instruction and students in the comparison schools received a drug education unit as part of the health curriculum. All students were pretested during the 6th grade prior to delivery of the programs, posttested shortly after completion, and resurveyed each subsequent year through the 10th grade. Three-stage mixed effects regression models were used to analyze these data. RESULTS: No significant differences were observed between intervention and comparison schools with respect to cigarette, alcohol, or marijuana use during the 7th grade, approximately 1 year after completion of the program, or over the full 5-year measurement interval. Significant intervention effects in the hypothesized direction were observed during the 7th grade for measures of students' general and specific attitudes toward drugs, the capability to resist peer pressure, and estimated level of drug use by peers. Over the full measurement interval, however, average trajectories of change for these outcomes were similar in the intervention and comparison conditions. CONCLUSIONS: The findings of this 5-year prospective study are largely consonant with the results obtained from prior short-term evaluations of the DARE curriculum, which have reported limited effects of the program upon drug use, greater efficacy with respect to attitudes, social skills, and knowledge, but a general tendency for curriculum effects to decay over time. The results of this study underscore the need for more robust prevention programming targeted specifically at risk factors, the inclusion of booster sessions to sustain positive effects, and greater attention to interrelationships between developmental processes in adolescent substance use, individual level characteristics, and social context.