The ratio of female-to-male median annual earnings for full-time/full-year workers stood at 0.79 in 2014 (DeNavas-Walt and Proctor 2015). While this ratio is up from the 1960 level of 0.61, a substantial gap remains. Moreover, convergence has slowed since 2000. A recent survey article by Blau and Kahn (2016) finds that while women's gains in market skills measured by education and work experience were important in explaining convergence over the period 1980-2000, these human capital variables account for only a negligible portion of the gap that remains. In fact, women now surpass men on most measures of educational attainment, but this advantage has not filtered through to parity in wages (Goldin, Katz, and Kuziemko 2006; Murphy and Topel 2014).The career dynamics of the gender gap for graduates of the Chicago Business School, as studied by Bertrand, Goldin, and Katz (2010), illustrate a common pattern. While women and men start their careers with similar earnings, a substantial gap arises over time, and the arrival of children is a major concurrent factor in the rising earnings gap. At least in this highly (and homogeneously) educated population, only a small share of the gender gap is due to premarket factors such as training and coursework; instead, family formation sets the gap in motion. Wood, Corcoran, and Courant (1993) and Goldin (2014) document similar patterns among graduates of the University of Michigan and Harvard law schools. Wilde, Batchelder, and