The 17 States reported 4,132 cases of sexual abuse by natal fathers and 2,241 cases by stepfathers. Victims of natal fathers tended to be younger than victims of stepfathers. Some variation by race was also evident. In terms of family composition, there was 2.2 children in natal father households and 2.3 in stepfather households. However, when the offender was a natal father, 7.9 percent of the cases involved more than one child in the family being abused, in contrast with 5.9 percent of stepfather families. Stress profiles of natal fathers and stepfathers were similar in many respects. Reports of a child suffering from a physical or medical disability were more common among families with stepfather abusers. On the other hand, natal father families showed significantly higher rates of insufficient income, marital problems or marital instability, and alcohol or drug problems. Implications of the study findings are discussed. Further research is recommended to provide information on continuity and discontinuity in parenting and on the degree of fathers' involvement in child care. 22 references, 2 tables. (Author abstract modified)