Recent estimates indicate that up to 90 percent of California residents with developmental disabilities will become victims of sexual abuse, assault, or exploitation during their lifetimes. Victims rarely report abuse, however, either because they are unaware that they are being victimized or because they are confused about the sexual activity and the offender's intent. Offenders often coerce victims into pacts of secrecy or exchange favors in return for compliance. In addition, developmentally disabled victims usually lack basic information about human sexuality and relationships. Parents should educate their children about these issues, although this process presents special difficulties for the parents of a retarded child. They need to be aware that the sequence of development of sexual interest is the same for all groups, although each phase occurs later for a retarded child than for a nonretarded one. Professional evaluators need to recognize that an effective assessment is part of the solution to the problem of sexual exploitation, in that the assessment process teaches the child through the use of the common language used to conduct the interview. Professionals must carefully document the interview, explain information at the appropriate level of comprehension, work backward from the event leading to the assessment, and address fears and feelings directly. Chart.