The National Incidence Study of Child Abuse and Neglect was a major, government sponsored effort to collect data on reported and unreported child abuse. It used a systematic representative sample methodology and very precisely developed definitions of child abuse. This paper review some of the main limitations of the study in regard to findings on sexual abuse. First, there is probably less "new" data in the study on sexual abuse than on other forms of abuse, since so many of the study cases of sexual abuse were "officially reported' cases. In addition, the study limited its definition of sexual abuse only to cases where a caretaker was the perpetrator , a definition that is much more restrictive than what is used in many treatment programs. Finally, the data on perpetrators has a number of problems that stem from the study's definitions of sexual abuse. The paper makes suggestions for future incidence type studies of sexual abuse.