The authors' goals in this article are to (a) describe a new task for the assessment of shifting attention between different affective stimuli, The Children's Attentional Shifting Task (CAST); (b) present the theoretical background for the development of the CAST; and (c) report initial information on the developmental appropriateness and validity of the CAST. The task was tested using a sample of kindergarten and 1st-grade children, 50% of whom had social and conduct problems. Preliminary analyses showed that the CAST was not subject to problems arising from fatigue or loss of interest. Moreover, children's ability to shift attention away from angry facial expressions was positively related to teachers' ratings of their ability to shift attention and parents' reports of children's emotion regulation. Shifting away from negative affect also predicted children's academic performance as reported by teachers. (Contains 3 figures, 3 tables and 1 note.)