Sex and gender contribute to the variation in pain experience. A range of biological, psychological, and social factors are relevant, which point to potential pain mechanisms and the reasons for this sex/gender-based variation. This review provides a brief critical overview of the evidence for these patterns. It draws on both experimental and clinical studies and identifies some of the biological and psychosocial factors that are thought to impact on men and women's pain. There are limitations and gaps in understanding, and numerous challenges exist, ranging from difficulties with concepts through to methodology. There is a focus on gender as a dimensional set of psychosocial constructs, as this offers one approach to help enhance our understanding of men and women's pain.