Over the past two decades, gender has become firmly established as a key analytical concept within bioarchaeology and related fields. Accordingly, researchers are increasingly interrogating its use within bioarchaeology, considering the theories used to identify, explain, and understand gender in the past, and challenging the methods used for reconstructing it. This chapter provides an overview of some of this work. Its goal is to enable researchers to gain enough familiarity with the study of gender that they can confidently identify additional appropriate theoretical literature and successfully incorporate gender into their own analyses. This includes the theoretical underpinnings for studying gender and related methods. Accordingly, this chapter surveys feminist theoretical work on gender and highlights its applications in bioarchaeology. Furthermore, it discusses the complexity and challenges of studying gender within bioarchaeology and how gender relates to other key concepts in the field. A brief case study on sex, gender, and status relative to mercury treatments for acquired syphilis in 17th to 19th century London demonstrates several aspects of theoretical work on gender in bioarchaeology. It also demonstrates some of the complexities involved in doing so and the insights that this practice can provide for understanding social identity in the past.