This study tested parts of the hypothesis that voyeurism, exhibitionism, toucheurism and frotteurism, obscene telephone calling, and at least some cases of the preferential rape pattern are all based on the same disturbance. In Part One, a frequency count of patients referred for one of these activities who subsequently reported having engaged in others of this same class was in accord with the clinical impression that there is a high degree of concomitance among at least some of these activities. In Parts Two and Three, relative preference for anomalous vs. normal erotic interactions was assessed by monitoring penile volume changes during verbally presented descriptions of corresponding situations. Part Two demonstrated that patients who suffered from one of the disorders in question other than voyeurism and who denied voyeuristic activity or tendencies, nonetheless responded more to narratives describing voyeuristic situations than did controls. Part Three showed that exhibitionists who denied toucheuristic activity or tendencies responded more to toucheuristic stimuli than did controls.