There have been profound changes in the role of marriage and marriage and cohabitation patterns in the last several decades. These shifts in marriage patterns would, in general, be expected to be accompanied by changes in the types of partners that individuals choose when they do form unions; i.e., in """"""""assortative mating"""""""" patterns. One implication of these changes is an increase in the number of single-parent households. To the extent that the health and overall well-being of children is enhanced by living with an intact family, these changes in family structure will have ramifications for the next generation. Another implication is an increase in income inequality across households. I propose to expand the literature on marriage and assortative mating, by conducting a thorough descriptive analysis of the changes in the patterns in the last several decades, and by developing and estimating an econometric model of the joint partner choice/union status decisions. The analysis will use data from the Panel Study of Income Dynamics, and the U.S. Census. This proposal includes a pilot study of the patterns in marriage and assortative mating with respect to education which suggests the following specific research questions: (1.) How does the relationship between education and the likelihood of marriage differ when cohabitors are treated as married couples? (2) Are assortative mating patterns different for cohabiting and married couples? (3.) What are the patterns in assortative mating with respect to characteristics such as parents' education and """"""""unobserved ability,"""""""" and how have they changed over time? (4.) Can the cohort differences in the marriage patterns be explained by differences in observables such as education, family policy, or marriage market conditions? (5.) Can changes in assortative mating be explained by changes in the pattern of selection into marriage? (6) Do women face a tradeoff between partner quality and union """"""""cohesion""""""""?