Report describes how the Federal Energy Management Program could use communities of practice as tools to stimulate organizational, social, and cultural change to support energy efficiency, renewable energy, and water conservation efforts. Done right, communities of practice have great potential to leverage existing resources. The paper describes the behavior and organizational principles that underlie communities of practices, provides examples of different types of communities of practice, for example, the American Council for an Energy-Efficient Economy Summer Study, EVALTALK, and the Home Energy Pros website. The paper also provides guidance about how to establish a community of practice and a checklist for doing so.