Smoking during deployments is a growing problem, particularly among junior-enlisted personnel, who have the highest smoking rates in the military. Few studies have examined reasons for smoking initiation among never smokers, relapse among former smokers, or increased smoking frequency among current smokers. We conducted 24 focus groups at four Air Force and two Army installations (N = 189) to examine the extent of smoking during deployment and to elucidate factors thought to contribute to new initiation, relapse, and increased smoking in a sample of junior-enlisted personnel and their supervisors. Important reasons for smoking included: (1) managing stress, boredom, anxiety, and sleep deprivation; (2) lack of alternate activities and privileges; (3) the perception that dangers in the field trumps the health impact of smoking; and (4) the role of the military environment in encouraging smoking. In addition, the phenomenon of new initiation and relapse to smoking in the field was discussed.