The study found that men's perception of a partner's interest in other men was a more important determinant of violence in the relationship than women's self-reported interest in other men, whether they had cheated in the current relationship, and their ability to find a good alternative mate. Men who perceived that their partners were interested in other men tended to engage in proprietary mate-retention tactics, but they were not more attentive. Men who engaged in proprietary mate-retention tactics tended to engage in violence against their partners. Women's proprietariness stemmed from perceptions that their male partners were interested in other women, and these perceptions had some validity; however, no significant link was found between female proprietariness and female violence against their partners. These findings provide additional evidence that male violence against a romantic partner stems, at least partly, from attempts to control female sexuality through threat and punishment of anticipated or suspected infidelities. Study participants were recruited from introductory psychology classes at the University of New Mexico. Participants were required to be in a heterosexual dating relationship for at least 1 month prior to their participation. Their partners also had to be willing to participate in the study. Married couples were not included in the sample, although couples could be engaged or living together. Participants were administered a questionnaire that measured relationship investment, relationship length, interest in others, perceived partner interest in others, male retention tactics, abusive behaviors, perception of one's value as a romantic partner, and infidelity in past and current relationships. 3 tables, 2 figures, and 41 references