Abstract: This article uses citations to the published opinions of judges on the federal courts of appeals who had 6 or more years tenure at the end of 1995 to estimate empirically the influence of individual judges. We rank judges on the basis of both total influence (citations adjusted for judicial tenure and other variables) and average influence (citations per published opinion). We also analyze the effects of factors that may be relevant to explaining differences in the influence of individual judges. These factors include both characteristics of the judges (for example, quality of law school, law school performance, sex, race, prior experience, political affiliation) and characteristics of the circuit in which they sit (such as the mix of cases in the circuit). In an appendix, we use citations to the published opinions in each circuit rather than to individual judges to measure the influence of circuits rather than individual judges.