What do people find attractive in others? This study tests four hypotheses about interpersonal attraction: the similarity, repulsion, optimal dissimilarity, and ideal partner hypotheses. To test these hypotheses, we manipulated the degree of correspondence between the temperaments of female subjects and five prospective dating partners. Each subject completed a temperament questionnaire and was then presented with computer-generated stimulus profiles of men that were correlated +1.0, +0.5, 0.0, -0.5, and -1.0 with her own profile. The subject then rated the "dating partners" in terms of pleasure and arousal. Support was found for the similarity, repulsion, and ideal partner hypotheses. Similar partners were most pleasurable and arousing; dissimilar partners were repulsive. In addition, independent of similarity, subjects were driven to seek a male with certain specific characteristics: sociability, a higher activity level, and a lower level of emotionality. This pattern suggests that individual differences interact with nomothetic laws in interpersonal attraction, and that both domains must be considered in a complete formulation of the attraction phenomenon.