Enhancing students' intercultural competences through international higher education requires a thorough understanding of the way in which these competences develop over time, how they relate to outcomes, and which factors predict their growth. To answer these questions, a three-wave longitudinal study was conducted among a sample of first-year students in an international university program (n = 425). Intercultural competences were operationalized through the five dimensions of the Multicultural Personality Questionnaire (MPQ): Cultural Empathy, Openmindedness, Flexibility, Social Initiative and Emotional Stability. We examined development of these traits across one year, as well as their relationship with stress, life satisfaction, and academic performance (GPA). Cultural background (local vs. international student) and prior international experience (yes/no) were included as predictors. Results show that MPQ scores at the beginning of the year negatively relate to change across semester 1, which in turn is negatively related to change across semester 2. These findings suggest the presence of ceiling effects in MPQ development. In semester 1, emotional stability acts as a buffer against stress. In semester 2, stress is lower among students with higher scores on cultural empathy, and lower scores on flexibility. Cultural empathy and social initiative relate positively to academic performance. No significant main effects were found for cultural background, or prior international experience. However, these predictors interact on openmindedness and social initiative: local students with no prior international experience show a significant increase in these dimensions across the first semester, whereas the others do not.