Two questions concerning the effect of physical abuse in early childhood on the child's development of aggressive behavior are the focus of this article. The first is whether abuse per se has deleterious effects. In earlier studies, in which samples were nonrepresentative and family ecological factors (such as poverty, marital violence, and family instability) and child biological variables (such as early health problems and temperament) were ignored, findings have been ambiguous. Results from a prospective study of a representative sample of 309 children indicated that physical abuse is indeed a risk factor for later aggressive behavior even when the other ecological and biological factors are known. The second question concerns the processes by which antisocial development occurs in abused children. Abused children tended to acquire deviant patterns of processing social information, and these may mediate the development of aggressive behavior.