The associations among socioeconomic disadvantage, amygdala volume, and internalizing symptoms in children and adolescents are unclear and understudied in the extant literature. In this study, we examined associations between socioeconomic status (SES) and amygdala volume by age across childhood and adolescence to test whether socioeconomic disadvantage would be associated with larger amygdala volume at younger ages but with smaller amygdala volume at older ages. We then examined whether SES and amygdala volume were associated with children's levels of anxiety and depression. Participants were 3- to 21-year-olds from the Pediatric Imaging, Neurocognition, and Genetics study (N = 1,196), which included structural magnetic resonance imaging. A subsample (n = 327; 7-21 years of age) completed self-report measures of anxiety and depression. Lower family income and parental education were significantly associated with smaller amygdala volume in adolescence (13-21 years) but not significantly associated with amygdala volume at younger ages (3-12 years). Lower parental education, but not family income, was significantly associated with higher levels of anxiety and depression, even after accounting for family history of anxiety/depression. Smaller amygdala volume was significantly associated with higher levels of depression, even after accounting for parental education and family history of anxiety/depression. These findings suggest that associations between SES and amygdala structure may vary by age. In addition, smaller amygdala volume may be linked with an increased risk for depression in children and adolescents.