To evaluate students exposed to Project Charlie at a primary school in London and to assess its impact on drug-related knowledge, attitudes, and behavior, children who participated in the program in 1992 were followed up in 1996 and compared with children who did not participate in the program. Three comparisons were made: (1) a sample of 44 students was randomly assigned by class to either receive Project Charlie or to act as a control and receive no drug education, and 34 students were successfully followed up in 1996; (2) a sample of 24 students who received Project Charlie was matched with a sample of 24 students who did not receive the program, and 42 students were successfully followed up in 1996; and (3) both of the preceding samples were added to a larger comparison sample of 233 students that consisted of all students who happened to be in secondary school classes of follow-up students in 1996. Program participants in the first comparison were significantly less likely to have used tobacco than controls. They were also less likely to have used illicit drugs but this was not statistically significant. Similar but statistically insignificant trends were found in the second comparison. Both tobacco and illicit drug use were significantly less common among program participants in the third comparison. While program participants did not appear to have more decision-making skills at long-term follow-up, they did show a significantly greater ability to resist peer pressure than controls in the first and second comparisons. Project Charlie had no long-term effect on knowledge but did have an impact on attitudes, with program participants expressing more negative attitudes toward drugs than controls in the first and third comparisons. Findings and a review of the literature on evaluations of primary school interventions lead the authors to conclude substantial and well-delivered primary school drug education programs can have a delaying effect on the onset of drug use. The program evaluation form used to obtain data from students is appended. 71 references and 18 tables