'Acquaintance' rape involves forces, unwanted intercourse by a person known to the victim, usually through subtle and nonviolent manipulations. The three main stages in acquaintance rape are intrusion, whereby the rapist engages in sexually oriented behaviors and conversations that make the potential victim uncomfortable; desensitization, whereby the potential victim believes the perpetrator's comments and actions are relatively harmless; and isolation, whereby the perpetrator takes advantage of or creates a situation of isolation with the victim. Self-protection to prevent acquaintance rape involves knowing the problem; knowing yourself, what you want, and what your limits are; and defending your limits and gaining control. Knowing the problem means taking seriously the possibility that an acquaintance, even a friend, is capable of rape. Knowledge of the warning signs of potential rape behavior is also important. Knowing yourself means being aware of your personality characteristics, such as passivity and a tendency to trust that others will do nothing to harm you, which may make you vulnerable to a rapist's manipulations. Defining limits means developing the will and the techniques for communicating to others what you want and do not want. Gaining control involves resisting others' efforts to make you do something you do not want to do. Exercises are presented to help persons develop the knowledge and techniques for preventing acquaintance rape.