This thesis examined how basic psychological needs relate to social anxiety and internalizing symptoms among Third Culture Kids, or children and adolescents who grow up across countries and cultures due to their parents’ international mobility. Drawing on Self-Determination Theory, the study focused on satisfaction and frustration of autonomy, competence, and relatedness among students aged 8–18 at an international school in the Netherlands (N = 113). 

Results suggest that competence frustration was the most consistent predictor of both social anxiety and internalizing symptoms, while autonomy satisfaction was specifically associated with lower internalizing symptoms. These findings suggest that internationally mobile youth may benefit from school- and family-level support that bolsters competence and agency by helping them feel capable in new academic, social, and cultural contexts, while giving them meaningful choice and voice in their everyday lives.