Early emotional understanding is fostered by mother-child conversation in which mothers elaboratively enhance children's understanding. Little is known of the broader relational and risk factors influencing maternal discourse style, how discourse content and quality are associated with children's emotion language, and how these predict emotion understanding. In this longitudinal study of a high-risk sample, attachment security and family risks were assessed when children were 2 years old. One year later, observations of mother-child emotion conversation yielded measures of maternal discourse content and quality, and children's emotion words and emotion labels. Child emotion understanding was independently assessed one year later as well. Central findings were: (1) content and quality of maternal discourse was negatively related to family risk factors and positively associated with secure attachment; (2) child emotion language in conversation was positively associated with secure attachment beyond the effects of child language and maternal discourse content; and (3) differences in emotion language ability predicted children's emotion understanding.