The Body Matrices (Frederick & Peplau, 2007; Gray & Frederick, 2012) contain 28 computer-generated images of shirtless men varying in body fat and muscularity and 32 images of women in bikinis varying in body fat and breast size. The male matrices present seven levels of muscularity and four levels of body fat. The female matrices present eight levels of body fat and four levels of breast size. Each matrix contains all possible combinations of these body fat and muscularity/breast size level (e.g., slender women with large breasts; heavier women with smaller breasts). Consistent with self-discrepancy theory (Higgins, 1987), they assess men’s and women’s perceptions of their current bodies and their ideal bodies, and discrepancies between these perceptions. They can be administered to adolescents and/or adults and are free to use. This chapter describes the development and psychometrics of The Body Matrices. Test-retest reliability was high for current and ideal bodies for men and women, and moderate to high for self-ideal discrepancies. BMI (self-reported height and weight) was strongly associated with current body images chosen by participants. The chapter provides the images, response scale, and scoring procedure. Logistics of use, such as permissions, copyright, and contact information, are provided for readers.