The Social Development Model (SDM) is a life course theory that integrates several extant criminological theories to specify the interactive social processes that lead to prosocial and antisocial behavior. Relatively little research has attempted to cross-validate this and other developmental theories of delinquency. The current study assesses the school and family processes that comprise SDM with a sample of Chicago public school students measured over three school years between fifth and eighth grades (n = 2,014). The data draw on student surveys tapping into multiple domains relevant to the explanation of problem behavior. Although overall model fit was marginal, the results of structural equation models largely support the SDM and its constituent paths. The implications for theoretical development and intervention are considered. (Contains 2 figures, 3 tables, and 14 notes.)