Gender schema theory proposes that children's acquisition of gender labels and gender stereotypes informs gender-congruent behaviour. Most previous studies have been cross-sectional and do not address the temporal relationship between knowledge and behaviour. We report the results of a longitudinal study of gender knowledge and sex-typed behaviour across three domains in children tested at 24 and 36 months (N = 56). Although both knowledge and sex-typed behaviour increased significantly between 2 and 3 years, there was no systematic pattern of cross-lagged correlations between the two, although some concurrent relationships were present at 24 months. Future longitudinal work might profitably focus on younger children using reliable pre-verbal measures of gender knowledge and employing a shorter lag between measurement times.