Objectives: Studying abroad is often considered a life-changing experience.However, research on studying abroad has not always disentangled selection from socialization effects, leading to uncertainty about the actual impact of this experience. In this 4-wave longitudinal study, we examined both selection and socialization effects of a 4-week intensive study abroad program on 17 psychosocial variables related to motivation, academic achievement, well-being, and self-reflection. Method:We used propensity score matching and multiple-group growth curve models to examine selection and socialization effects in a sample of sojourners (n = 145) and non-sojourners (n = 291). Results:We found selection effects for several variables related to students' motivation and well-being. Contrary to our predictions, we found no evidence for socialization effects of studying abroad on any of the outcome variables. Conclusions:Students who are relatively more intrinsically motivated and emotionally healthy appear to be more likely to study abroad. However, studying abroad for one month does not appear to lead to meaningful and lasting psychological change, on average. Our results highlight the need to examine both selection and socialization effects of study abroad programs with longitudinal data and well-matched comparison groups.