Public relations research has gradually incorporated the study of advocacy organizations. However, little research has focused on social movements in particular. Through a content analysis of all public tweets sent by Black Lives Matter (BLM) over a four-year period, this study examined the message strategies used on Twitter by the social movement as a means to share information, build community, and promote action. Consistent with research on other types of organizations, informational messages proved to be the most common. The study also analyzed the influence that these strategies had on audience engagement in terms of replies and retweets. Findings suggest that community building messages garner the most retweets but no significant differences were found in terms of replies.