Over the last six decades there has been less co-authorship in leading economic history journals than in leading general economics journals. There has also been a strong, monotonic increase in co-authorship in economic history journals that roughly parallels general economics journals but sharply differs from leading history journals. Increased co-authorship cannot be explained by increasing use of econometrics or large data sets; rather, it is likely due to common changes in incentives facing economic historians and economists. Finally, co-authorships in economic history are more likely to be formed of individuals of different seniority compared to economics generally.