The theory of courtship disorder suggests voyeurism, exhibitionism, frotteurism, and preferential rape (a paraphilic preference for coercive sex) are expressions of a common underlying disturbance. Previous research has demonstrated that voyeurism, exhibitionism, and frotteurism are relatively likely to co-occur; however, their associations with rape are weaker. One explanation is that rapists are more heterogeneous and may not always be motivated by a paraphilic interest in coercive sex. Paraphilic interests can be identified using phallometric testing, but the sensitivity of the test is attenuated by voluntary control over erectile responding. Another approach is to look for a behavioral marker associated with paraphilic rape-proneness. Freund (1990) has argued that exhibitionism may be the "hub" of courtship disorder because exposing one's genitals to a stranger is rare in control subjects. We predicted that rapists who also engaged in exhibitionistic activity would be more likely than other rapists to also engage in other expressions of courtship disorder, i.e., voyeurism and frotteurism. To rule out the possibility that rapists who report exhibitionistic activity only differ in their willingness to report anomalous sexual behavior, we also predicted no difference between the groups in their self-reported involvement in other paraphilic activities such as sadism or masochism, or paraphilic target preferences such as fetishism or transvestism. Finally, we predicted no difference between groups in their willingness to admit to attempting or committing rape. The results supported our predictions, and lend credence to the notion of preferential rape as an expression of courtship disorder. Moreover, these results suggest that the presence of another paraphilia, particularly exhibitionism, may be useful as a behavioral marker for paraphilic rape-proneness.