There are 2.1 million current military servicemembers and 21 million living veterans in the United States. Although they were healthier upon entering military service compared to the general U.S. population, in the longer term veterans tend to be of equivalent or worse health than civilians. One primary explanation for the veterans' health disparity is poorer health behaviors during or after military service, especially areas of physical activity, nutrition, tobacco, and alcohol. In response, the Department of Defense and Department of Veterans Affairs continue to develop, evaluate, and improve health promotion programs and healthcare services for military and veteran health behavior in an integrated approach. Future research and practice is needed to better understand and promote positive health behavior during key transition periods in the military and veteran life course. Also paramount is implementation and evaluation of existing interventions, programs, and policies across the population using an integrated and person centered approach.