In this paper we review current definitions and measurement approaches used to assess individual differences in children's temperament. We review the neural bases of temperamental reactivity and self-regulation and propose that these constructs provide a framework for examining individual differences and developmental change in emotion-cognition interactions across development. Studies are reviewed in which some well-documented contextual effects on the expression of temperament can be interpreted in terms of the influence of biological and non-biological factors on CNS functioning. We conclude with ideas regarding future directions for the study of individual differences and developmental change in cognition-emotion interactions as they are shaped throughout development.