This paper investigates what motivates young people to volunteer for peace-keeping or peace-enforcing missions and how their motives change between pre- and post-deployment. Data include information about social and military background, and motives for more than 600 soldiers, 444 of whom answered the survey both before and after deployment. Soldiers are deployed to different missions under the same circumstances. To conceptualize motives among soldiers, we use factor analysis and find three factors: challenge, self-benefit, and fidelity. Challenge represents an occupational orientation; fidelity, an institutional orientation; and self-benefit, a desire for adventure. Exploiting the within-subject design of our data, we find that pre- and post-deployment motives vary significantly according to the type of mission and soldiers’ previous experiences (first-timers or experienced soldiers). Our results suggest that after the mission, peace-keepers are generally more disappointed than peace-enforcers. Our results also show that self-benefit motives are important for younger soldiers with only a high school education, and that this group usually serves as peace-enforcers during their gap year.