Background: Cumulative risk research has established the deleterious effects of co-occurring risk factors on child behavior outcomes. However, extant literature has not addressed potential differential effects of cumulative risk at different points in development and has left open questions about whether a threshold model or a linear risk model better describes the impact of cumulative risk on behavior outcomes. The current study examined the impact of cumulative risk factors (i.e., child maltreatment, inter-parental violence, family disruption, low socioeconomic status, and high parental stress) in early and middle childhood on child behavior outcomes in adolescence. Methods: Using data from an ongoing longitudinal study of at-risk urban children (N = 171), the cumulative effects of these five risk factors across early and middle childhood were investigated. Results: The findings support the cumulative risk hypothesis that the number of risks in early childhood predicts behavior problems in adolescence. Evidence for a linear but not a threshold model of cumulative risk was found; the more risks present, the worse the child outcome. Moreover, the presence of multiple risks in early childhood continues to explain variations in predicting adolescent behavior outcomes even after including the effects of risk in middle childhood. Conclusions: The results support the need for comprehensive prevention and early intervention efforts with high-risk children, such that there does not appear to be a point beyond which services for children are hopeless, and that every risk factor we can reduce matters.