Initiation of substance use before the age of 15-16 is a distinct risk factor for a variety of mental health problems and eventual drug abuse. Using multimethod, multiagent measures of child, family, and peer antecedents at age 9-10, we studied the longitudinal effects in an at-risk sample of 206 boys. Event history analysis was used to examine the antecedents to patterned alcohol and tobacco use, as well as experimentation with marijuana between age 11-16. Univariate models revealed that at Grade 4, most constructs were prognostic of boys’ early substance use. Multivariate event history models clarified the risk and protective structure associated with tobacco, alcohol, and marijuana use. The level of intercorrelation among the predictor variables, however, suggested that family, peer, and child characteristics were inextricably connected within an ecology of development. A structural equation prediction model suggested a higher order construct, «childhood risk structure.»