Internationally adopted postinstitutionalized (PI) children are at risk for lower levels of emotion understanding. This study examined how postadoption parenting influences emotion understanding and whether lower levels of emotion understanding are associated with behavior problems. Emotion understanding and parent mental state language were assessed in 3-year-old internationally adopted PI children (N = 25), and comparison groups of children internationally adopted from foster care (N = 25) and nonadopted (NA) children (N = 36). At 5.5-year follow-up, PI children had lower levels of emotion understanding than NA children, a group difference not explained by language. In the total sample, parent mental state language at age 3 years predicted 5.5-year emotion understanding after controlling for child language ability. The association of parent mental state language and 5.5-year emotion understanding was moderated by adoption status, such that parent mental state language predicted 5.5-year emotion understanding for the internationally adopted children, but not for the NA children. While postadoption experience does not erase negative effects of early deprivation on emotion understanding, results suggest that parents can promote emotion understanding development through mental state talk. At 5.5 years, PI children had more internalizing and externalizing problems than NA children, and these behavioral problems related to lower levels of emotion understanding.