In 2009, Toni Carey and Ashley Hicks created Black Girls RUN! (BGR), a blogturned national running organization created to help tackle the growing obesity epidemic in the Black community. In recent years, BGR has proven to be an important cultural, social, and health phenomenon inspiring more than 100,000 women to hit the pavement. This dissertation explores the influence and appeal of BGR with various approaches, including a critical textual analysis of 1,062 Instagram posts tagged #blackgirlsrun. That analysis is combined with a broad cultural contextualization supported by ten qualitative interviews, participant observation, and auto-ethnography. Findings show that the dailyuse of #blackgirlsrun on social media has spurred a national dialogue on Black womens health issues and also generated a virtual health community where women can seek out information and support that spans across traditional barriers of distance and time. The various cultural and social practices occurring within the stream of #blackgirlsrun reinforce the role of evolving communication technology in community formation. The viral nature of the groups message demonstrates the importance of cultural relevance in promoting health and empowering target audience members to adopt new behaviors. These findings suggest that Black Girls RUN! and the social media hashtag, #blackgirlsrun, have significant implications for the fields of mass communication and health promotion.