The Department of Veterans Affairs (VA) has made treatment and care of Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) veterans a priority. Researchers face challenges identifying the OIF/OEF population because until fiscal year 2008, no indicator of OIF/OEF service was present in the Veterans Health Administration (VHA) administrative databases typically used for research. In this article, we compare an algorithm we developed to identify OIF/OEF veterans using the Austin Information Technology Center administrative data with the VHA Support Service Center OIF/OEF Roster and veterans' self-report of military service. We drew data from two different institutional review board-approved funded studies. The positive predictive value of our algorithm compared with the VHA Support Service Center OIF/OEF Roster and self-report was 92% and 98%, respectively. However, this method of identifying OIF/OEF veterans failed to identify a large proportion of OIF/OEF veterans listed in the VHA Support Service Center OIF/OEF Roster. Demographic, diagnostic, and VA service use differences were found between veterans identified using our method and those we failed to identify but who were in the VHA Support Service Center OIF/OEF Roster. Therefore, depending on the research objective, this method may not be a viable alternative to the VHA Support Service Center OIF/OEF Roster for identifying OIF/OEF veterans.