The purpose of this study was to determine how Child Protective Services (CPS) investigators decide to substantiate mothers for failure-to-protect from sexual abuse. A case-comparison study was used to compare 31 mothers who were and 62 mothers who were not substantiated for failure-to-protect by CPS. The multivariate analysis showed that mothers who did not consistently believe the sexual abuse occurred and who did not consistently act protectively were more likely to be substantiated. In addition, if they knew about the abuse from more than one source were less supportive of the children; and had a substance abuse problem, a mental health problem or were being battered, then they were more likely to be substantiated. Investigators appear to apply criteria consistently to substantiate mothers. (Contains 2 tables.)