It was hypothesized that people who indicated that they would act anti-socially would make significantly lower estimates of the costs associated with their behavior than people who indicated they would act pro-socially. The study also investigated the effects of selected personality and situational variables on the cost estimates. It was hypothesized that the characteristics of the victim of the anti-social act, Sociopathy, Locus of Control, and the importance assigned certain values would influence subjects' estimates of the costs associated with their behavior. Questionnaires which measured Sociopathy, Locus of Control orientation, and the value importance were given to 107 undergraduates twice. Two weeks after the second administration, subjects indicated if they would return or take money that had been lost by an individual, an institution, or unidentified owner; in addition they made estimates of the costs associated with their actions. The hypothesis regarding cost estimates and anti-social actions was confirmed. Also, it was found that owner characteristics, Sociopathy, and Locus of Control were significantly related to the cost estimates. The viability of reward/cost model of pro-anti-social behavior and the influence of personality and situational variables on the costs specified by the model were discussed.