Gender is a fundamental aspect of human identity. It is so basic that it is seldom considered; rather, it is taken as a given. However, when a person’s gender differs from expected norms the person may experience much distress, which can lead to mental health and interpersonal challenges. This, in turn, can trigger significant difficulties in important realms of function and adaptation. This entry on gender differences offers an overview of gender: what it is, how it impacts identity and functioning, and how being differently gendered can create an atypical developmental experience for a child or adolescent. This entry acknowledges, however, that gender is complicated and multifaceted. It is informed by culture and context and viewed and constructed differently in different parts of the world ...