A half-million children are believed to be sexually abused each year in the United States. In 1995, the American Medical Association declared sexual assault "a silent violent epidemic." The majority of efforts to stop child sexual abuse have focused on punishing abusers and treating victims and their families; prevention programs are uncommon and rely on educating children to report sexual abuse. This case study describes the evaluation of the first public health campaign designed to target adults for prevention. A baseline assessment of attitudes, awareness, knowledge, and policies was conducted in Vermont to identify facilitators and barriers to adult prevention of child sexual abuse. These included predisposing factors (50% of Vermont residents did not know the characteristics of an abuser), enabling factors (60% of Vermont residents did not know where to refer someone who may have sexual behavior problems), and reinforcing factors (when focus group participants knew an abuser, they were less likely to take action). This process guided the intervention, which included a broad-based media campaign targeting adults; a one-to-one communications strategy that provided information to agencies working with families at risk and a toll-free helpline for adults in an abuse situation; and a systems change strategy designed to educate decision-makers and leaders. Program evaluation measures included a random-digit dial survey, focus groups, a survey of Vermont decision-makers, and other data sets. The successes and limitations of these interventions, both as strategies in themselves and as data sources for evaluation, are discussed.