The purpose of this text is to provide a review of the empirical research and conceptual discussions surrounding gender and to examine the implications of gender for relationships and health. The focus of this book goes beyond sex alone--whether one is biologically male or female--to explore the roles that society has assigned to men and women and the other variables that co-occur with sex, such as status and gender-related traits. The implications of social roles, status, and gender-related traits for relationships and health are examined. This is why the book is titledThe Psychology of Genderrather thanThe Psychology of Sex.Gender is a term that represents the social and cultural forces that influence men and women in our society. The book discusses the "psychology" of gender because the focus is on the individual in the social context. The primary focus is not on biology and anthropology, although their contributions to the study of gender are included. Rather than review every single topic related to gender, I examine the implications of gender for two broad domains of research: relationships and health. These domains are chosen, first, because they are central to our lives. Friendships, romantic relationships, and relationships at work have a great impact on our day-to-day functioning. Psychological wellbeing and physical health are important outcomes in their own right. A second reason for the focus on relationships and health is that these are domains in which clear sex differences have been documented. These sex differences cannot be attributed to biology alone; thus, relationships and health are domains for which gender, the social category, may play a role. The book is divided into three sections, with each section building on the previous one. First, the nature of gender and the development of gender roles is presented. In the first chapter, I provide a brief overview of the scientific method and discuss the difficulties in conducting research on gender, including the philosophical and political issues that pervade this arena. I then provide a brief history of the psychology of gender, which includes discussions of the various instruments used to study gender (Chapter 2). I also discuss our attitudes toward gender and gender roles, as well as gender-role stereotypes (Chapter 2). I then turn to the research literature to provide the current data (Chapter 3) and theory (Chapter 4) on sex differences in cognitive, emotional, and social domains. In Chapter 4, I also discuss different theories of gender-role development, such as evolutionary theory, social learning theory, social role theory, and gender schema theory. In Chapter 5, I discuss the implications of gender and gender roles for aggression, including rape, domestic violence, and sexual harassment. In Chapter 6,.I discuss the implications of gender and gender roles for achievement. Thus, in this first section of the book, I provide important information on the similarities and differences between men and women and the theories that explain any observed differences. The data and the theories are important for understanding the subsequent sections of the book that address the implications of gender for relationships and health. The second section of the book begins with a discussion of men's and women's communication and interaction styles (Chapter 7). These findings have implications for the specific relationships discussed: friendship (Chapter 8) and romantic relationships (Chapter 9). Recent research on cross-sex friendship and gay and lesbian relationships are included in these chapters. The role of gender in relationships is critical to understanding the third section of the book, how gender influences health. The third section begins with an overview chapter documenting sex differences in mental and physical health and theories as to their origins (Chapter 10). Health is broadly construed in this book