The findings supported the primary hypothesis: All family types other than one in which the biological father of all children in the household was living with the family had a higher likelihood of CPS involvement. This hypothesis withstood the inclusion of a host of selection factors and was robust to alternative model specifications, with one exception; after adjusting for selection factors, the study found no consistent evidence that maternal dating was associated with increased CPS involvement. Based on these findings, CPS agencies may be justified in viewing men in the home who are not the biological father of a child in the home as a risk factor for that child's maltreatment. Although the study cannot conclude that such risk is greater for children living with a social father than for children living with a single mother, it may be important for CPS to devise appropriate interventions that address the presence and role of social fathers in children's lives. Study data were obtained from the FFCW, a longitudinal cohort study of 4,898 children born between 1998 and 2000 in 20 U.S. Cities. Families in the study sample were categorized according to whether the mother was living with a male partner or spouse, was involved in a dating relationship, or was not romantically involved. Families in which the mother was romantically involved with a man were further delineated by whether the partner was the biological father of none, some, or all of the children in her household. The primary outcome variable was CPS involvement. 3 tables and 35 references