Abstract This article presents an experiment designed to test the impact of temptation and self-selection into an opportunistic environment on an individual’s likelihood of engaging in dishonest behavior. In doing so, this experiment is the first of its kind to isolate the relationship between temptation and cheating as its primary focus, to create a randomized control group for comparative purposes, and to be conducted without deceiving subjects. The evidence shows that people who tempt themselves to cheat are more likely to cheat. Further, people who self-select into the opportunistic setting cheat to a greater extent than individuals placed into the same opportunistic condition by random assignment. There are no gender differences in choice of environment or likelihood of cheating. An individual’s self-reported value of ethics predicts honest behavior but only for subjects who consider their moral principles to be “very important” in their everyday lives. The results have direct implications for any environment where individuals can self-select into an opportunistic setting.