Gender and sexuality are often problematically considered to be irrelevant to very young children. This Handbook surveys, challenges, and advances the theories, research approaches, and practices around gender and sexuality in the early years, foregrounding early childhood as a crucial site for the construction and deconstruction of gender and sexuality. The Handbook features chapters by leading academics, practitioners, and policy makers based in Australia, Canada, India, Indonesia, South Africa, the UK, and the USA. It covers a range of key critical theories, methods, and practices, including engagements with post-developmentalism, feminist, Black feminist, queer, and trans theories, intersections with indigeneity, race, and class, ethnography, action research, care ethics, and sexual health. The Handbook illuminates the importance of attending to gender and sexuality in early childhood across various sites, including in the classroom, at home, in policy, and more.