This guide details how coalitions and organizations can effectively work to change public policies that impact underage drinking. The guide first explains the elements of public policy including laws, regulations, and the policies and practices of public institutions. Tips are provided on effective ways to impact each of these elements so that a clear, consistent message can be delivered throughout the community on the dangers of underage drinking. The guide gives examples of opportunities that can jump start a public policy initiative, and includes a variety of useful tools that can help communities first determine what kind of public policy initiative they need. Samples of letters and a telephone script are provided.