Principles of crime prevention can be illustrated with a triangle whose three sides are labeled "desire," "target," and "opportunity." The elimination of any one side will prevent a crime from being committed. Crime-prevention actions that are the most effective reduce or remove the "opportunity" for a criminal to commit a crime. A crime-prevention practitioner or older volunteer should be knowledgeable about the technical aspects of crime prevention activities, but success in eliciting crime- prevention actions from others lies in being an effective salesman, educator, and resource manager. The role of the crime- prevention practitioner is to change attitudes, persuade individuals and communities to accept their responsibilities, and initiate community action programs. To achieve these objectives, the practitioner must develop and implement awareness programs, educate the public about crime prevention, inform people about the limitations of the criminal justice system, and motivate people to take individual and collective action. This paper provides examples of effective crime prevention programs in the areas of check theft, bank robbery, robbery of bus drivers, criminal fraud, and residential burglary.