This article asks broad questions about the evidence on the effect of gender on judging. Do female judges in fact speak in a different voice? The evidence is mixed. Taken as a whole, the most systematic research suggests that gender matters in certain kinds of cases, in particular discrimination claims, which is one of the reasons why diversity should matter for selecting judges. But these cases are not a large part of the Supreme Court’s workload. Nor will statistical correlations predict the votes of any individual judge, which is why diversity is only one of the factors that should affect appointments.