AbstractArmy male enlisted personnel were tested in two experiments to assess the psychological correlates of volunteering for a hazardous combat simulation, (Experiment 1) and a riskless, psychological experiment (Experiment 2). Subjects were given a biographical and personal habit questionnaire, the IPAT Anxiety Scale, Rotter's Locus of Control Scale, and Torrance and Ziller's life experience inventory. Results from Experiment 1 indicated that volunteers were significantly less anxious, and more willing to take risks than were nonvolunteers. Noncommissioned officers, smokers, laterborn children, and children of lower socioeconomic class parents were significantly overrepresented among the volunteers for this hazardous experiment. In Experiment 2, which solicited volunteers for a routine, nonhazardous experiment, the only variable to discriminate the volunteers from the nonvolunteers was mothers' education level. Results are in agreement with findings, using college students, that volunteer samples differ significantly from nonvolunteer samples, and that the characteristics that discriminate these two groups vary as a function of situational factors.