The aim of the study was to examine the mediating and moderating roles of social support in the acculturation-mental health link, and to investigate how these processes combine with self-esteem to affect mental health change. Questionnaire data were collected twice from 137 immigrant students, first at the upstart in junior high school, and then again a year later (8th and 9th grade). Acculturation was described in positive terms as a developmental process towards gaining competence within more than one sociocultural setting. Perceived discrimination and ethnic identity crisis were included as risk factors in this process. A model of structural relations was tested, which after some modifications demonstrated a close fit to the data. The results supported our suggestions of two indirect paths of effects of acculturation on mental health change: one through culture domain-specific social support and another through self-esteem. Self-esteem was also identified as a mediator of identity crisis. Significant interaction effects between social support and culture competencies were demonstrated in addition to buffer effects of class and family support in relation to identity crisis and discrimination respectively. The study adds to our understanding of positive and negative developmental pathways in multicultural societies.