Justice Sonia Sotomayor's assertion that female judges might be better than male judges has generated accusations of sexism and potential bias. An equally controversial claim is that male judges are better than female judges because the latter have benefited from affirmative action. These claims are susceptible to empirical analysis. Using a data set of all the state high court judges in 1998–2000, we estimate three measures of judicial output: opinion production, outside state citations, and co-partisan disagreements. For many of our tests, we fail to find significant gender effects on judicial performance. Where we do find significant gender effects for our state high court judges, female judges perform better than male judges. An analysis of data from the U.S. Court of Appeals and the federal district courts produces roughly similar findings.