Executive function abilities, including working memory, inhibitory control, and the flexible volitional shifting of the focus of attention provide a foundation for reflection on experience, reasoning, and the purposeful regulation of behavior. These abilities and their underlying neurobiology, however, are inherently malleable and influenced by characteristics of individuals and contexts. Implications of this malleability for research on the development of executive function in early childhood, for the prospect that these abilities can be fostered and promoted by specific types of activities, and for issues relating to the reliable and valid measurement of executive function are considered.