Much of the research on the economic integration of immigrants centers on educational and occupational mobility from the first through third generation. Although intermarriage is a key component of both old (Gordon 1964) and new (Alba and Nee 2003) perspectives on immigrant assimilation, the role of intermarriage in the economic integration of immigrants remains poorly understood. As the population of immigrants and children of immigrants has increased in the past few decades, the increasing availability of marital partners with the same national origin has led to an increase in endogamous marriages in the second generation. What are the implications of the decline in intermarriage for the economic outcomes of the second generation of post-1960s immigrants? We use pooled cross-sectional data from the IPUMS-CPS 1996-2010 to investigate the relationship between assortative mating by national origins and the economic well-being of adult children of immigrants. We find that (1) children of immigrants who partner with members of the same national-origin group have lower income and living standards relative to those who intermarry; (2) children of immigrants who partner with a native-born spouse or cohabiting partner are not economically advantaged as compared to those who partner exogamously with first and second generation immigrants; and (3) the economic gains from intermarriage depend on the race and ethnicity of both partners, with Asian immigrants the only group to show no effect of assortative mating.