This chapter explores the approaches and methods used to determine sex from the human skeleton. Skeletal sex determination in medico-legal or archaeological context is a key component of personal identification and for establishing the remainder of the biological profile. Sexing methods are typically divided into two categories: morphological (shape) and metric (size). Morphological aspects of the human skeleton that are sex-specific are found primarily in the pelvis and, less so, in the other bones of the body. Metric differences between the sexes are mainly found in the skull but also in the postcranial skeleton. Both categories have varying accuracy rates, with the pelvis being the best indicator overall; however, some metric methods are accurate >90% of the time. This chapter details several morphological techniques and provides a discussion of the statistical aspects of metric sex determination. As with any rigorous science, a solid foundation in basic techniques is necessary, and that foundation is the goal of this chapter.