Do we become a different person when hitting the road? Personality development of sojourners

International mobility is a prevalent life event that particularly affects university students. The aim of this longitudinal study was twofold: First, we examined the impact of international mobility on personality (Big Five) change, separating self-selection effects from socialization processes. Second, we extended prior analyses on the association between life events and personality development by investigating the mechanisms that account for socialization processes. In particular, we assessed whether individual differences in the fluctuation of support relationships serve as an explanatory link. We used a prospective control group design with 3 measurement occasions. A sample of university students, containing both short-term (i.e., 1 semester) and long-term (i.e., 1 academic year) sojourners (N = 527) along with control students (N = 607), was tracked over the course of an academic year. Multivariate latent models revealed 3 main findings: First, initial (pre-departure) levels of Extraversion and Conscientiousness predicted short-term sojourning, and Extraversion and Openness predicted long-term sojourning. Second, both forms of sojourning were associated with increases in Openness and Agreeableness and a decrease in Neuroticism above and beyond the observed self-selection. Third, the acquisition of new international support relationships largely accounted for the sojourn effects on personality change. These findings help to fill the missing link between life events and personality development by establishing social relationship fluctuation as an important mediating mechanism.