The National Center on Child Abuse and Neglect indicated that in 1986 there was an incidence rate of child sexual abuse of 2.5 children per 1,000 annually, for a tripling of reported incidence since 1980. Although these studies begin to reveal the magnitude of the problem, they do not fully define the incidence or prevalence of child sexual abuse because their data are limited to cases handled by child protective services agencies. The most reliable sources for true incidence figures on child sexual abuse appear to be in the self-reports of past and present victims and offenders. In recent studies that have used polygraph exams to improve the veracity of self-reports, the high rates of offenses committed by some sexually abusive youths have been corroborated. All estimates thus far, however, must be approached with caution, because of the many unknown factors. It is not known how many sex offenders are never reported or if those who are caught are representative of all. Also, just as the self- reports of victimization may be unreliable, the self-reports of sex offenders are highly suspect. 23 references