Intermarriage with natives is a key indicator of immigrant integration. This article studies intermarriage for 138 immigrant groups in Sweden, using longitudinal individual level data. It shows great variation in marriage patterns across immigrant populations, ranging from over 70 percent endogamy in some immigrants groups to below 5 percent in other groups. Although part of this variation is explained by human capital and the structure of the marriage market, cultural factors (values, religion, and language) play an important role as well. Immigrants from culturally more dissimilar countries are less likely to intermarry with natives, and instead more prone to endogamy.