In recent decades, scholars of world cultural diffusion have begun to examine the structure of the world society itself, finding evidence of regionalization within the network of international nongovernmental organizations (INGOs). There is little research, however, on how the structure of world society shapes processes of transnational diffusion. In this paper, I propose that the regionalization of world society, measured through INGO membership composition, structures the transnational diffusion of cultural norms like LGBT associations. Analyzing an original, comprehensive dataset of 3,141 domestic, voluntary LGBT associations founded between 1979 and 2009, I find that countries embedded in anti-LGBT regions are more resistant to the diffusion of domestic LGBT associations. I further find that the negative effect of embeddedness in anti-LGBT regions on domestic LGBT association founding is weakened by dependence on Western foreign aid. The findings highlight the importance of examining the composition of INGOs as well as attending to the role of regional culture in studies of transnational diffusion.