Child Sexual Abuse (CSA) is one widely cited risk factor for Sexually Intrusive Behavior (SIB) among boys. To identify variables that moderate the early onset of SIB in a sample of boys, alleged victims of sexual abuse, the current study involved a prospective examination of all investigations of male CSA victims and those of boys aged under 14 who were suspected of committing SIBs on other children in Israel over a 10-year period. Comparing victims with and without SIB records revealed differences on personal and family factors as well as on the characteristics of abuse. A regression model controlling for age and family factors correctly classified over three quarters of the subjects based on reported experiences of abuse. The data help identify characteristics of the abuse that facilitate the early onset of SIB among male victims of CSA.