Grit can be viewed as a facet of conscientiousness consisting of the two sub-facets perseverance of effort and consistency of interest. Although ample research illustrates the importance of grit for educational attainment, little is known about its developmental trajectories. The goal of the present study was to examine the development of self-perceptions in the two grit facets during educational stays abroad in young adulthood. We measured grit in a sample of 179 German sojourners, who went abroad for some type of educational stay, immediately before the start of their stay abroad (T1), 3 months afterwards (T2), and 15 months afterwards (T3). We compared the developmental trajectories across T1 and T2 with a control group of 112 Germans staying at home during this period. Multivariate latent change score models showed an increase in perseverance of effort between T1 and T2 in the group of sojourners, which did not emerge in the control group and persisted throughout T3. Consistency of interest did not change between T1 and T2, but sojourners showed an increase in consistency of interest between T1 and T3. This change was positively predicted by the time sojourners had spent abroad. Although we found different developmental trajectories for perseverance of effort and consistency of interest, substantial correlated change between these facets indicated similar processes to account for change in both traits. We discuss implications for research on the development of grit as well as the role of educational stays abroad.