Short-term mating mechanisms should be activated only under conditions in which, ancestrally, the benefits were recurrently greater and the costs were recurrently lower than those of other potential mating strategies. The purpose of this dissertation was twofold: 1) to identify benefits and costs of short-term mating to men and women and to rank them based on magnitude, 2) and to identify how sex-specific adaptive individual differences previously known to affect mating success shift perceptions of the magnitude of, and likelihood of receiving, potential benefits and costs. To identify and rank potential benefits and costs, participants listed up to ten potential benefits and costs men and women may experience when engaging in short-term mating. A second group of participants rated the benefits and costs for how beneficial and how costly they are. A second study examined how sex-specific adaptive individual differences shift perceptions of the magnitude of, and likelihood of receiving, the nominated benefits and costs. Participants completed several questionnaires designed to measure relevant demographics and family history, personality, and previous and current mating experiences. Participants also provided their perceptions of the magnitude of each of the benefits and costs, and the perceived likelihood someone could receive each outcome. Results indicated women’s perceptions did not differ as a function of their self-perceived mate value, exposure to early environmental stress, relationship status or satisfaction, but did differ as a function of their feelings of sexual regret. Similarly, men’s self-perceived mate value, relationship status and satisfaction did not influence perceptions of short-term mating, but the amount of effort currently invested into mating and feelings of sexual regret did. Overall, this dissertation contributes a novel extension of previous research on short-term mating. This is the first study to examine the costs to women, and the benefits and costs to men of short-term mating, and the first study to examine how individual differences may shift perceptions of those benefits and costs. Findings from the current set of studies provide a more thorough understanding of men’s and women’s evolved mating psychology and highlight fruitful avenues for future research. / text