This introduction, to an issue on privacy as a social issue and behavioral concept, discusses what privacy is, by examining definitions and theories of privacy, and what privacy does, by reviewing the benefits of obtaining privacy and the costs of failing to achieve and of losing privacy. It provides a possible bridge between social psychological and social issues approaches to privacy and examines privacy as a social issue for Americans as citizens, health-care recipients, consumers, and employees. It then briefly explores behavioral aspects of privacy, including indicators of privacy's importance and the generally overlooked status of privacy in psychology.This issue is primarily about privacy as a social issue and secondarily about privacy as a behavioral concept. This reflects what I have found in my readings over the last decade or so. I believe there has been an increasing level of scholarly interest in privacy as a social issue. The debate often emphasizes threats to privacy, how serious the threats are, and if and how these threats should be addressed. By comparison, there continues to be relative indifference to privacy, as a theoretical or research interest, among psychologists in general. Both themes are discussed below.This introduction discusses what privacy is by examining issues in defining privacy and how privacy has been construed in two influential theories of privacy. It then examines what privacy does by reviewing theory and research on the benefits of obtaining privacy and the costs of failing to achieve and of losing privacy. Given this base, we suggest a bridge between psychological and social issues