This systematic review searched 9 electronic databases and reviewed all available published scientific data on the adjustment of internationally mobile children and adolescents who relocate with their families. An initial search in December 2021 yielded 9,433 studies. Key findings: family functioning, personality openness, self-efficacy, and length of stay positively predict adjustment outcomes. Ambivalent attachment style and repatriation anxiety hinder adjustment. The review calls for more research on psychological factors and interaction between third culture and psychosocial adjustment. Published in Frontiers in Psychology (open access) and also available via PubMed.