To identify cases reported nationwide between January 1983 and December 1985, high-level day care licensing and child protection officials in all 50 States were contacted, a search of newspaper clippings was conducted, and 60 sexual abuse specialists were interviewed. Data were collected on the 270 identified cases, and indepth study was undertaken on a random sample of 43 of these cases. The 270 facilities involved 1,639 children. Perpetrators included day care staff, volunteers, and others (bus drivers, janitors, outsiders). Of cases, 83 percent involved a single perpetrator; and 40 percent of perpetrators were women. Girls were more frequently victimized than boys (62 versus 38 percent), and half of all cases involved only a single reported victim. No specific victim or offender profile could be discerned. Touching and fondling was the most common form of abuse, and penetration (including oral, digital, or other object) occurred in 93 percent of cases. Two-thirds of cases occurred in the facility's bathroom. Parents and the victims were the most common source of disclosure. Victims exhibited a variety of symptoms including fear, sleep disturbance, regression, and inappropriate sexual behavior. Only 21 percent of initial allegations were substantiated, and multidisciplinary team approaches were most effective in terms of outcomes and impact on victims. In substantiated cases, licensing sanctions were somewhat more successful than criminal prosecution, and 54 percent of facilities with substantiated cases remained open after investigation was terminated. Recommendations for prevention, detection, investigation, and treatment are included. 1 figure.