This article presents the results of biographical research involving women and men over 60, with a focus on the issue of gender identity and how it changes during aging. The study provided answers to three main research questions: Are there distinguishable patterns of forming one’s own gender identity that are specific to senior age, and if so, which ones? Do the patterns change during the ageing process, and if so, how? What determines how a person experiences the transformation of their gender identity in senior age? The article also discusses the ways elderly men and women define their own femininity or masculinity and the significance in this regard of such biographical experiences as losing a spouse, retirement, and bodily aging. There is also an attempt at a typology of senior femininities and senior masculinities.