The purpose of this study was to evaluate music teacher professional development (PD) practice and policy in the United States between 1993 and 2012. Using data from the nationally representative Schools and Staffing Survey (SASS) spanning these 20 years, I examined music teacher PD participation by topic, intensity, relevance, and format; music teachers' top PD priorities; and the reach of certain PD-supportive policies. I assessed these descriptive results against a set of broadly agreed-on criteria for "effective" PD: content specificity, relevance, voluntariness/autonomy, social interaction, and sustained duration. Findings revealed a mixed record. Commendable improvements in content-specific PD access were undercut by deficiencies in social interaction, voluntariness/autonomy, sustained duration, and relevance. School policy, as reported by teachers, was grossly inadequate, with only one of the nine PD-supportive measures appearing on SASS reaching a majority of teachers in any given survey year. Implications for policy, practice, and scholarship are presented.