State and local policymakers and concerned citizens can use this guide to assess the existing laws and regulations in their jurisdiction; identify gaps, loopholes, and areas for improvement; identify strengths upon which effective enforcement strategies can be built; persuade legislatures and local policymaking bodies that changes are needed; and motivate enforcement and regulatory agencies to strengthen enforcement of existing laws and policies. Information on regulations that are most important in reducing youth access to alcohol and underage drinking are presented under three categories, depending on which aspect of youth access to alcoholic beverages and their use they address. Regulations under "commercial availability" focus on the practices of alcohol retailers such as liquor or grocery stores and bars; regulations under "social/public availability" address noncommerical sources of alcohol (such as older friends) and noncommercial venues where youth consume alcoholic beverages (such as parties); and regulations under "youth possession" pertain to deterring youth from attempting to purchase or consume alcoholic beverages. For each type of regulation, the guide discusses the available research literature on effectiveness, the features of good laws, pitfalls to avoid, and examples of States or communities that have used the regulation successfully. Each section of the guide includes "best practice" recommendations. The guide advises that the regulatory strategies outlined cannot be viewed in isolation; their success and continuation can be assured only by building a foundation of community participation and activism and developing complementary policies and programs designed to shift community norms and expectations. 85 references