The present issue of Epidemiologic Reviews is dedicated to better understanding the health of men and women who have served in the military. There are 13 articles that discuss a range of physical and mental health concerns among both military personnel who are currently serving and those who served in the past. The corresponding research provides insight into issues that are directly relevant and of keen interest to clinicians and investigators. The articles illustrate some of the obstacles to conducting rigorous epidemiologic research when seeking to inform the health issues of those who serve in the military and of veterans. Within the United States, they point to opportunities for the Department of Defense and Department of Veterans Affairs (VA) to address existing gaps in knowledge. The VA in particular can take advantage of its research infrastructure, altruistic veteran population, and clinical and administrative databases. In the era of multinational military interventions, international counterparts of the Department of Defense and VA should collaborate in the collection of data on relevant military exposures and also in the characterization of short- and long-term health effects related to service to better inform health needs. The work included in this issue is a call to the global research community to continue to invest resources to better characterize military service and its impact on health. Finally, these articles serve as a testament to the additional health burden carried by many of the women and men who have provided service to their country.