In light of recent scholarship about teachers leveraging social media to support their continuing professional development, this article documents an investigation of school board policies governing teachers' use of social media. Focusing on 30 traditional public school systems within a 10-county region in the Midwestern United States, the author collected social media policies and conducted an ethnographic content analysis to build an understanding of the policies that stand to guide teachers' professionally oriented participation online. Of the 30 public school districts included in the study, 19 districts published policies specific to teachers' use of social media. Reporting the study's findings, the author addresses the districts' efforts to craft policies that define social media, reiterate relevant pre-existing policies and support educational uses of social media. Implications for teachers, teacher educators and policymakers are included.