The document discusses engagement as the true measure of successful Facebook communities. It defines engagement as requiring dialogue and interaction between consumers and organizations. The document provides best practices for engagement, including encouraging engagement outside brand domains, collaborating with fans, rewarding loyalty, having an authentic digital identity, listening to communities, responding to inquiries, setting community guidelines, avoiding canned responses, and empowering community managers. It also provides case studies on the key engagement elements for Crystal Head Vodka and the film Revolution, including strong customer service, appreciation of user-generated content, compelling branding, and addressing difficult questions.