What is the current state of psychological knowledge about lesbians, gay men, and bisexuals? This book presents definitive treatments of both current and classical psychological research and theory on lesbian, gay, and bisexual identities across the lifespan. Not only is the current status of the topic surveyed, and important research summarised from the last two decades, but promising directions for future research are also identified. This book is the most comprehensive review of psychological research on sexual orientation available and unique in focusing on lesbian, gay and bisexual people in relationships, families, and in communities.