The Mother’s and Children’s Emotions (M&E) study is a longitudinal research design with three timepoints, which followed children from toddlerhood, into the preschool period, through school age. Mothers and children came into the lab for a variety of laboratory-based observation tasks. Mothers and their children completed interaction tasks, like freeplay activities, and children’s expression of pleasure, fear, and frustration were also observed. Laboratory tasks also assessed children’s self-regulatory skills. Mothers also completed questionnaires about their own and their children’s behavior. Teachers also completed questionnaires about children’s behaviors at the school-age timepoint.