Gender norms are essential barometers of gender equality; inequitable gender norms are indicative of core inequalities in society that undermine the health of many groups. Fundamentally embedded in the gender system, prescriptive and restrictive gender norms have been shown to have deleterious effects on the health of women, men, girls and boys, as well as gender and sexual minorities. Gender norms are mutable, and there is potential to target and transform harmful and inequitable gender norms to drive gender equality. Gender-transformative approaches are needed, but a necessary first step is to identify and benchmark restrictive and inequitable gender norms, monitor change and progress, and highlight areas where interventions can be targeted for greatest effect. Efforts to do this are currently stymied by a lack of fit-for-purpose data. Routinely collected, population representative data on gender norms is urgently needed. This is vital to supporting and progressing gender equality and will contribute substantially to lifting population health.