Many sexuality educators and professionals, even those involved in program development and planning, are not aware of the biological and social factors involved in gender identity development in youth. As such, this topic is often not as well addressed in whole life educational curricula as better understood topics, such as reproductive anatomy, puberty, and contraception. This review article is intended to provide an overview of gender identity development in childhood and adolescence, in order to encourage better integration of comprehensive understandings of gender identity into new sexuality education curricula through the inclusion of specific information about transgender and other gender nonconforming identities.