The mix of cases in the U.S. Court of Appeals for the District of Columbia Circuit differs markedly from the case mix of other U.S. courts of appeals. The implications of this difference for judicial workload and judgeship needs, however, have been unclear. At the request of the Subcommittee on Judicial Statistics of the Judicial Conference Committee on Judicial Resources, we conducted this study to assist the subcommittee in assessing judgeship needs in the D.C. Circuit.