Program managers and correctional administrators contacted during NIJ-sponsored research on the management of sex offenders in the community frequently asked how they might best evaluate their programs. In planning an evaluation, three crucial points to remember are the need for researcher objectivity but not isolation, the need for evaluation to be more than a one-time event, and the possibility of some degree of evaluation regardless of resources and programs. Three forms of evaluation are program documentation and monitoring, process evaluations, and impact evaluations. Evaluation through documentation and monitoring is a standard evaluation model that almost any program can implement and use to assess effectiveness. Process evaluations consider how an outcome is produced rather than just the outcome itself. The strongest impact evaluations use research designs and measurement techniques that are modeled after laboratory techniques. Each of the evaluation approaches require different levels of resources and expertise. However, every program must be informed by ongoing evaluation if it is to be effective on an ongoing basis. The authors are members of the United States Bureau of Justice Assistance State Reporting and Evaluation Program's national advisory board. Footnotes, appended sample data collection form for sex offender programs, and 20 references