We study the implications of traditional gender norms for legislators’ engagement with women’s issues. We exploit information on the popularity of gender-related interests available from Facebook to capture variation in gender attitudes at the municipal level within Italy, a geographical resolution that would otherwise be unavailable. We then develop a granular Gender Norms Index (GNI) by replicating a region-level survey-based benchmark measure via machine learning algorithms. After validating our index by showing that it reflects other cultural and socio-economic variables, we leverage this local variation in norms to isolate their impact on legislators’ policy activity in the Italian Parliament. We show that while female legislators are in general more likely to sponsor gender-related bills than men, the engagement is substantially smaller if they were born in more gender-conservative towns. The results are unlikely to be fully explained by party and constituency influences. These findings highlight the importance of social norms and sexist culture in lawmaking, possibly slowing down reform for the expansion of women’s rights