Parent-youth relationships and parenting are critically important to adolescents' development. The present study examined associations between parenting behaviors (which included observed parent emotion expression and negative and positive parenting behaviors during a parent-adolescent interaction) and adolescent brain structure, and sex differences in associations, in 66 12-14 year-olds. The study found that 1) among all adolescents in the sample, greater parent negative emotion expression in parent-youth interactions was associated with greater adolescent gray matter volume (GMV) in the left hippocampus, 2) parent positive emotion expression was not associated with adolescent GMV, 3) several associations differed by sex. These findings suggest that parenting is important for adolescent brain structure and future work should consider this by sex.