Abstract Following the release of the first COVID‐19 vaccinations many people utilized social media to promote vaccination among their social circles. These attempts to persuade others to get vaccinated ranged from positive encouragement (e.g., emphasizing the prosocial benefits and positive outcomes) to shame and threats (e.g., name calling and threating to end friendships over vaccination status). The present study investigated how these different social media messages affected COVID‐19 vaccination intentions. In June 2021, shortly after vaccines had been made freely available to anyone over the age of 16 in the United States, unvaccinated participants read a manipulated Twitter message designed to be either encouraging or shaming . Message‐type did not significantly affect intentions to become vaccinated against COVID‐19; however, participants who saw the encouraging message reported that the post made them feel more likely to get vaccinated. Self‐efficacy was also manipulated but did not reveal any significant effects. Additional analyses suggest that having personal experience with COVID‐19 moderates reactions to these different messages. We discuss limitations and promising avenues for future research on the effects of social media messages on health behaviors.