Stressful experiences, self-evaluations, and self-standards associated with multiple contexts of development (i.e., school, family, sports/athletics) were investigated as predictors of initiation of sexual activity during the transition to adolescence. A sample of 134 seventh and eighth graders was followed as part of a 4-wave, 2-year longitudinal study. Survival analysis was used to examine measures at Time 1 as predictors of the timing of initiation of sexual activity. Reports of greater stressful experiences and less favorable self-evaluations associated with school as well as weaker self-standards associated with family were significant predictors of less time to initiation of sexual activity. For sports/athletics, however, reports of more positive self-evaluations predicted less time to initiation. Results of mediational analyses indicated that self-evaluations for the school context partially mediated the linkage that stressful experiences relating to this context exhibited with initiation of sexual activity.