Discriminatory gender norms can intersect and interact with other dimensions of discrimination-such as age, race, ethnicity, disability, education status, and sexual orientation-to shape individuals' experiences and impact their health and wellbeing. This interaction is referred to as intersectionality. Although the theory has been in circulation since the late 1980s, only recently has it gained traction in low-income and middle-income settings, and it has yet to fully penetrate global research on adolescence. The social and structural intersectional drivers of adolescent health and wellbeing, particularly during early adolescence (age 10-14 years), are poorly understood. The evidence base for designing effective interventions for this formative period of life is therefore relatively small. In this Review, we examine how gender intersects with other forms of disadvantage in the early stages of adolescence. Analysing data from hybrid observation-intervention longitudinal studies with young adolescents in 16 countries, our aim is to inform the health and wellbeing of girls and boys from a range of social contexts, including in conflict settings. Adolescents' perceptions about gender norms vary by context, depend on individual opinion, and are shaped by socioecological drivers of gender inequalities in health. Shifting those perceptions is therefore challenging. We argue for the importance of applying an intersectionality lens to improve health and wellbeing outcomes for young adolescents and conclude with five practical recommendations for programme design and research.