||According to Sexual Strategies Theory (Buss & Schmitt, 1993), individuals with higher mate values have more mating opportunities available to them. This study examined the relationship between mate value, as measured by Body Mass Index (BMI), and infidelity, a sexual behavior that involves mating with multiple partners. I predicted that, based on the increased availability of mates, women with higher mate values would commit infidelity more often than lower value subjects, but that in general, fewer women would report cheating than men. A questionnaire measuring self-reported BMI and two types of infidelity, intercourse cheating and non-intercourse cheating, was distributed to 518 student and community participants. Contrary to prior studies (e.g. Wiederman, 1997), more women than men reported cheating. However, of those subjects who reported cheating, men committed more episodes of intercourse cheating than women. There was no difference in the number of episodes of non-intercourse cheating. BMI positively correlated with the number of episodes of intercourse cheating for both sexes, but did not correlate with the number of episodes of non-intercourse cheating. The significance of these findings to evolutionary theories of mating behavior is explored, several study limitations are acknowledged, and suggestions are made for future research on infidelity.