In this paper we have described an integrative causal model of the development of antisocial behavior in children and adolescents. The present model primarily integrates several previous models, but offers some new testable hypotheses. We believe that stable individual differences in propensity to antisocial behavior reflect variations in a number of dimensions of predisposing temperament and cognitive ability, each with its own genetic and environmental influences. The dimensions of predisposing temperament include oppositionality, harm avoidance, and callousness. Genetic influences are predicted to have only indirect effects on antisocial behavior via their influence on predisposition and on the youth's social environment. Environmental influences are expected to be important contributors to antisocial propensity, but these environmental influences reflect, in part, the genetic influences on the dimensions of predisposition (i.e. genotype-environment covariance). We also hypothesize that the levels of influence of the factors that determine individual differences in antisocial propensity change with development, such that genetic influences are of greater magnitude in early childhood and social influences contribute more strongly during later childhood and adolescence (both through independent effects and genotype-environment covariance). However, low levels of heritable predisposing child characteristics may protect against peer influences at all ages.