A 2-year study completed in 1988 explored the validity and incidence of such allegations, as well as the special problems posed by such cases from initial investigation through the final custody determination. The study included surveys of judges, data from five court sites, and data from 169 cases involving sexual abuse allegations in custody disputes in 12 States. Results suggest that from less than one percent to as many as 8 percent of custody disputes involved sexual abuse allegations. Of the 169 cases studies, investigators believed 50 percent to be true; and in 17 percent, a determination of validity could not be made with any certainty. The remaining cases were not believed to involve abuse, but investigators felt that most of these allegations had been made in good faith. While legal professionals were skeptical of allegations arising in post-divorce cases, such cases were slightly more likely to be viewed as actual abuse cases than those arising in other situations. Results also suggest that well-prepared expert evaluations of the family by a mental health professional can aid judges in reaching decisions in such cases. Such evaluations should include family sexual histories, details of the alleged abuse, relationship dynamics, cognitive functioning of all parties, child development and peer relations, and observed child behaviors. 11 footnotes.