This paper, using data from the 2000 Iran Demographic and Health Survey and a range of time-varying district-level contextual information derived from the 1986 and 1996 censuses of Iran, applies a discrete time hazard model to study ethnic differences in women's transition to first marriage. The model specification accounts for both spatial and temporal changes in the socio-economic context of transition to marriage. We found ethnic-specific responses on women's marriage timing to changes in the socioeconomic context between the mid 1970s and 2000. Some ethnic groups appear to be more resistant to change despite sharing similar changes in their socio-economic context.