We document patterns of intermarriage between immigrants and natives during a period of unprecedented growth in the size and diversity of America’s foreign-born population. Roughly one in six U.S. marriages today involve immigrants and a large share includes U.S.-born partners. Ethno-racial background clearly shapes trajectories of immigrant social integration. White immigrants are far more likely than other groups to marry U.S.-born natives, mostly other whites. Black immigrants are much less likely to marry black natives or out-marry with other groups. Intermarriage is also linked with other well-known proxies of social integration—educational attainment, length of time in the country, and naturalization status. Classifying America’s largest immigrant groups (e.g., Chinese and Mexican) into broad panethnic groups (e.g., Asians and Hispanics) hides substantial diversity in the processes of marital assimilation and social integration across national origin groups.