Using retrospective union, birth, and education histories that span 1980-2003, this study investigates nonmarital childbearing in contemporary Russia. We employ a combination of methods to decompose fertility rates by union status and analyze the processes that lead to a nonmarital birth. We find that the increase in the percentage of nonmarital births was driven mainly by the growing proportion of women who cohabit before conception, not changing fertility behavior of cohabitors or changes in union behavior after conception. The relationship between education and nonmarital childbearing has remained stable: the least-educated women have the highest birth rates within cohabitation and as single mothers, primarily because of their lower probability of legitimating a nonmarital conception. These findings suggest that nonmarital childbearing Russia has more in common with the pattern of disadvantage in the United States than with the second demographic transition. We also find several aspects of nonmarital childbearing that neither of these perspectives anticipates.