Section 2, Mood and Anxiety Disorders, is the longest, with five chapters. Ronald Kessler’s opening chapter reviews and critiques explanatory hypotheses for gender differences in major depression presented in epidemiologic studies from the biological and psychosocial traditions. His critique culminates in a section designed to focus future research along promising lines. The next chapter, coauthored by the book’s editor and Elizabeth Young, suggests that an interaction of biological and psychosocial factors at a critical stage (between 10 and 15 years of age) might explain why depression is more prevalent among adolescent girls than boys. The next chapter, by Michael Thase, the editor, Susan Kornstein, and Kimberly Yonkers, is especially important for clinicians because it reviews the research literature on the gender differences in response to available treatments for depression—including variants of counseling and psychotherapy, antidepressant medications, and ECT. The following chapter, by Naomi Breslau, Howard Chilcoat, Edward Peterson, and Lonni Schultz, reports on a study in which they explored the role anxiety disorders play in depression for women and for men. The next chapter also focuses on anxiety disorders. Authors M. Katherine Shear, Ulrike Feske, and Catherine Greeno review the literature on four psychosocial factors relevant to the greater prevalence of these disorders in women, and they conclude with a discussion of treatment implications.