[영문]What role do cultural norms play in shaping individual behaviour and how does this relationship change with rapid socio-economic development? While modernization and convergence theories predict a weakened relationship between culture and behaviour as individuals rely less on family and community members for economic opportunities, recent research suggests that such norms can persist and continue to influence behaviour. We explored this question for Indonesia, asking whether cultural norms for age at marriage and post-marriage residence?as embodied in local ethnicity-based laws and customs known as 'adat'?relate to actual marriage behaviour. We demonstrate that adat norms are strong predictors of marriage behaviour, both over time and net of large increases in educational attainment. Our results suggest more generally that traditional marriage norms can persist even when a society is in the process of rapid socio-economic development.