This article examines mothers' support for children's interests and, specifically, emotional processes in mothers that may explain why they display different levels of support with children of different temperaments. We observed 114 mothers and their 14-27 month-old children during a laboratory interaction. Mothers rated children on three dimensions of temperament: activity, anger proneness, and social fearfulness. As expected, activity predicted mothers' anger, disappointment, and low support for children's interests. Social fearfulness predicted mothers' worry, low anger, low disappointment, and high support for children's interests. Mediational tests verified that (1) mothers' emotions often mediated the relation of child temperament to mothers' supportive behavior, and (2) children's compliance often mediated the relation of child temperament to mothers' emotions. Mothers tended to report negative emotion and to display relatively unsupportive behavior with children whose temperaments corresponded to attributes considered relatively undesirable for their sex.