This study examined factors associated with teens' adherence to a multiple health behavior cancer preventive intervention. Analyses identified predictors of trial enrollment, run-in completion, and adherence (intervention initiation, number of sessions completed). Of 104 teens screened, 73% (n = 76) were trial eligible. White teens were more likely to enroll than non-Whites ([chi][squared][1] df = 4.49, p = 0.04). Among enrolled teens, 76% (n = 50) completed the run-in; there were no differences between run-in completers and noncompleters. A majority of run-in completers (70%, n = 35) initiated the intervention, though teens who initiated the intervention were significantly younger than those who did not (p less than 0.05). The mean number of sessions completed was 5.7 (SD = 2.6; maximum = 8). After adjusting for age, teens with poorer session engagement (e.g., less cooperative) completed fewer sessions (B = -1.97, p = 0.003, R[squared] = 0.24). Implications for adolescent cancer prevention research are discussed. (Contains 1 table and 1 figure.)