Treatment outcome for sexually abused preschool-age children and their parents was assessed, comparing the effectiveness of a cognitive-behavioral intervention to nondirective supportive treatment. Sixty-seven sexually abused preschool children and their parents were randomly assigned to either (1) cognitive-behavioral therapy adapted for sexually abused preschool children (CBT-SAP) or (2) nondirective supportive therapy (NST). Treatment consisted of 12 individual sessions for both the child and parent, monitored for integrity with the therapeutic model through intensive training and supervision, use of treatment manuals, and rating of audiotaped sessions. Parents completed the Child Behavior Checklist, the Child Sexual Behavior Inventory, and the Weekly Behavior Report to measure a variety of emotional and behavioral symptoms. Within-group comparison of pretreatment and posttreatment outcome measures demonstrated that while the NST group did not change significantly with regard to symptomatology, the CBT-SAP group had highly significant symptomatic improvement on most outcome measures. Repeated-measures analyses of variance demonstrated group x time interactions on some variables as well. Clinical findings also supported the effectiveness of the CBT-SAP intervention over NST. Findings provide strong preliminary evidence for the effectiveness of a specific cognitive-behavioral treatment model for sexually abused preschool children and their parents.