As the United States moves forward with health reform, the communication gap between researchers and policy makers will need to be narrowed to promote policies informed by evidence. Social media represent an expanding channel for communication. Academic journals, public health agencies, and health care organizations are increasingly using social media to communicate health information. For example, the Centers for Disease Control and Prevention now regularly tweets to 290,000 followers. We conducted a survey of health policy researchers about using social media and two traditional channels (traditional media and direct outreach) to disseminate research findings to policy makers. Researchers rated the efficacy of the three dissemination methods similarly but rated social media lower than the other two in three domains: researchers' confidence in their ability to use the method, peers' respect for its use, and how it is perceived in academic promotion. Just 14 percent of our participants reported tweeting, and 21 percent reported blogging about their research or related health policy in the past year. Researchers described social media as being incompatible with research, of high risk professionally, of uncertain efficacy, and an unfamiliar technology that they did not know how to use. Researchers will need evidence-based strategies, training, and institutional resources to use social media to communicate evidence.