Refugees frequently experience symptoms of posttraumatic stress and depression, which impede their acculturation in the new host country where they are resettling. There are few longitudinal studies investigating predictors of mental health and acculturation during the early postmigration period. We conducted a longitudinal study of 298 Iraqi refugees, assessing them upon arrival to the U.S. and 1 year after migration. Premigration trauma was associated with increased PTSD and depressive symptoms at baseline, and with decreased acculturation 1 year later. Resilience was associated with depressive symptoms at 1-year follow-up, but not with other resettlement outcomes (PTSD symptoms, English-language skills, or acculturation). PTSD and depressive symptoms at baseline predicted the same symptoms at 1-year follow-up, but not any other resettlement outcomes. The number of chronic diseases at baseline predicted worse PTSD and depressive symptoms, acculturation, and English language skills at 1-year follow up. Postmigratory exposure to daily stressors and less social support predicted worse 1-year outcomes. Results suggest that interventions that aim to improve mental health and promote acculturation among refugees should assess their history of trauma, chronic disorders, and psychological symptoms soon after migration, and promptly provide opportunities for social support.