Does Class Size Affect the Gender Gap? A Natural Experiment in Law

We study a unique natural experiment in which Stanford Law School randomly assigned first-year students to small or large sections of mandatory courses from 2001 to 2011. We provide evidence that assignment to small sections closed a slight (but substantively and highly statistically significant) gender gap existing in large sections from 2001 to 2008; that reforms in 2008 that modified the grading system and instituted small graded writing and simulation-intensive courses eliminated the gap entirely; and that women, if anything, outperformed men in small simulation-based courses. Our evidence suggests that pedagogical policy—particularly small class sizes—can reduce, and even reverse, achievement gaps in postgraduate education.