Confidential self-report data obtained on 107 adult male child sexual abusers were analyzed to test theoretical propositions concerning the role of attachment problems in the onset of sexual offending. Offenders' parent-child attachment relationships were most frequently characterized by affectionless control, reflecting low parental care and high overprotection and control. Offenders reported significantly less secure attachment with their fathers than with their mothers. Overall, weak continuity from childhood attachment to trait (general) adult attachment was found, with insecure attachment more stable than secure attachment. Childhood attachment problems, particularly with fathers, were more clearly reflected in state adult attachment (i.e., in the month preceding sexual offending onset) than in trait adult attachment. Offenders who were in an adult intimate relationship prior to their onset sexual offense reported significant state increases in attachment avoidance, and their onset offenses were more likely to involve a female familial victim. Offenders who were not in a relationship prior to offending onset were younger, and their onset sexual offenses occurred in much more diverse circumstances. These findings provide tentative evidence that directly and indirectly implicates offenders' attachment problems specifically in the onset of their sexual abuse behavior. Implications for developmental prevention and early intervention, situational prevention, and offender treatment are discussed.