To assess: (a) the relative impact of monitoring and peer involvement among six cohorts of African-American youth in their mid-adolescent years, over a decade of research in one urban area, and (b) the consistency of the impact of the two influences over time. Baseline data were collected from six cohorts involving 1279 low income African-American youth aged 13 to 16 years involved in community based studies conducted over a decade in an urban area. Self-reported behaviors, and perceptions of parental monitoring and peer risk-involvement were assessed through structured questions. Data were analyzed by frequency distribution, one-way ANOVA, and multiple logistic regression. There was a rapid increase in sexual activity and substance use behaviors during mid-adolescence. Monitoring had a protective influence on substance use behaviors and sexual activity, but had no impact on condom use or drug trafficking. Peer involvement influenced all evaluated risk behaviors. The influences overall did not statistically change over time. Despite the marked increase in risk behaviors during mid-adolescence, monitoring and peer involvement both influenced adolescent behaviors across each cohort.