在社会学中，性别认同是指一个人对自己性别上的认同（无论是将自己视为男性、女性、或某些非传统观点的性别），不过也可以用来指人们根据他们所认为的性别角色现象（如衣着、发型等等）而对个体所赋予的性别。当一个人的性别身分不同于他们的生理特征，他们可能会遇到性别焦虑症。

性别认同会受到各种社会结构的影响，包括了个人的道德及政治立场、工作地位、信仰与家庭，会随着时间和社会环境而改变价值观。

男子气的女生会爱与男生一起打球，或在行为举止上作出男性化的行为；而比较阴柔的男生可能会对女性化产生认同，而终日与自己的「姊妹」在一起。及一些中性打份的男性和女性，即使他们的行为举止与同性不相似，但可能与其他异性恋者的性取向并无不同。

Gender identity is one's personal experience of one's own gender. All societies have a set of gender categories that can serve as the basis of the formation of a person's social identity in relation to other members of society. In most societies, there is a basic division between gender attributes assigned to males and females, a gender binary to which most people adhere and which enforces conformance to ideals of masculinity and femininity in all aspects of sex and gender: biological sex, gender identity, and gender expression. In all societies, some individuals do not identify with some (or all) of the aspects of gender that are assigned to their biological sex; some of those individuals are transgender or genderqueer. Some societies have third gender categories.