This preliminary study evaluated a brief intervention, based on the theory of planned behavior, designed to encourage high school students to practice testicular self-examination (TSE). Ninety-nine male ninth and 10th grade students were exposed to a message challenging beliefs about outcomes of performing TSE as suggested by the theory of planned behavior, a message providing information about TSE and testicular cancer, or a control message, after which they completed a questionnaire operationalizing components of the theoretical model. Four weeks later, students reported their practice of TSE. As predicted, students exposed to the theory-based message reported a stronger intention to perform TSE and, at follow-up, were more likely to report having performed the exam than study participants exposed to other messages. Data provide partial support for the utility of the theory of planned behavior as a framework for constructing health-promoting messages. Future research recommendations are offered.