Men who have sex with men continue to be severely and disproportionately affected by the HIV/AIDS epidemic in the United States. Effective antiretroviral therapy has altered the HIV epidemic from being an acute disease to a chronic, manageable condition for many people living with HIV. The pervasiveness, low cost, and convenience of short message service suggests its potential suitability for supporting the treatment of conditions that must be managed over an extended period. The purpose of this proof-of-concept study was to develop, implement, and test a tailored short message service-based intervention for HIV-positive men who have sex with men. The messages focused on reducing risk-taking behaviors and enhancing HIV knowledge, social support, and patient involvement. Participants reported strong receptivity to the messages and the intervention. The authors detected a statistically significant increase in HIV knowledge and social support from baseline to follow-up. Among participants who received sexual risk reduction messages, the authors also detected a statistically significant reduction in reported risk behaviors from baseline to follow-up. Results confirm the feasibility of a tailored, short message service-based intervention designed to provide ongoing behavioral reinforcement for HIV-positive men who have sex with men. Future research should include a larger sample, a control group, multiple sites, younger participants, and longer term follow-up.