Data from large prospectively collected anterior cruciate ligament (ACL) cohorts are being utilized to address clinical questions regarding ACL injury demographics and outcomes of ACL reconstruction. These data are affected by patient and injury factors as well as surgical factors associated with the site of data collection. The aim of this article is to compare primary ACL reconstruction data from patient cohorts in the United States and Norway, demonstrating the similarities and differences between two large cohorts. Primary ACL reconstruction data from the Multicenter Orthopaedic Outcomes Network (MOON) in the United States and the Norwegian National Knee Ligament Registry (NKLR) were compared to identify similarities and differences in patient demographics, activity at injury, preoperative Knee injury and Osteoarthritis Outcome Score (KOOS), time to reconstruction, intraarticular pathology, and graft choice. Seven hundred and thirteen patients from the MOON cohort were compared with 4,928 patients from the NKLR. A higher percentage of males (NKLR 57%, MOON 52%; P