We evaluate opinion assignment and opinion authorship on the U.S. Courts of Appeals. We derive theoretical explanations and predictions for opinion assignment that are motivated by the Courts of Appeals' distinct institutional setting. Using an original dataset of sexual harassment cases, we test our predictions and find that female and more liberal judges are substantially more likely to write opinions in sexual harassment cases. We further find that this pattern appears to result not from policy-driven behavior by female and liberals assigners, but from an institutional environment in which judges seek out opinions they wish to write. Judicial opinions are the vehicles of judicial policy, and thus these results have important implications for the relationship between legal rules and opinion assignment and for the study of diversity and representation on multimember courts.