Perceived social support can help immigrant youth to deal with developmental acculturation: the simultaneous resolution of developmental and acculturative tasks. This person-oriented three-wave comparative study investigated perceived social support trajectories in two immigrant and one non-immigrant group. We investigated whether similar social support trajectory classes can be found across groups, whether developmental and/or acculturation-related processes predict class membership, and whether social support trajectory classes associate with changes in self-efficacy. The sample comprised 1326 ethnic German immigrant and 830 non-immigrant adolescents in Germany, and 1593 Russian Jewish adolescents in Israel (N = 3749; M[subscript age] = 15.45; SD = 2.01; 50% female). Results revealed two social support trajectory classes across all and within each group: a stable "well-supported class" and a low but "increasingly-supported class." Respective to the increasingly-supported class, membership in the well-supported class was associated with commonality in developmental predictors (female gender, high involvement with family and peers) in all groups and specificity in acculturation-related predictors (higher heritage and host culture orientation) in immigrant groups. Patterns of self-efficacy over time matched social support trajectories of both classes in all groups. Findings indicate that stakeholders looking to support immigrant adolescents should be aware of the nuanced coaction of development and migration.