This research was designed to find out more about the characteristics of fathers who sexually abuse their daughters, with the goal of helping to prevent such abuse and to identify possibly high risk populations. The sample consisted of 118 recently identified incestuous biological fathers and a matched comparison group of 116 non-abusive biological fathers. The men were interviewed at length about their childhood experiences, family life, and sex and social histories. The incestuous fathers also provided detailed information on the sexual contacts with the daughter. The comparison fathers were simply asked about their relationship with their daughter. The study found the incestuous fathers to be a heterogeneous group on a variety of dimensions. Contrary to popular conceptions about incestuous fathers, some molested very young children; others molested older children. A large proportion molested children outside the family in addition to the incestuous abuse, while others only molested family members. Some had a general arousal to children; others did not. Five distinct types of incestuous fathers were identified: sexually preoccupied; adolescent regressives; instrumental sexual gratifiers; emotionally dependent; and angry retaliators. Incestuous fathers as a group manifested disturbances or traumas that may be useful in understanding the sources of their behavior and identifying high risk populations. Incestuous fathers did appear to have been less involved in caring for their daughters prior to the onset of abuse. (ABL)