The concept "executive function," which broadly refers to the psychological processes involved in the conscious control of action and thought, occupies a central place in the study of cognition and cognitive development. However, while adequate as a working definition, this understanding is vague and imprecise. In this chapter, we examine contemporary approaches to executive function development that operate as behavioral descriptions, and as biological or psychological explanations. We argue that, in order to avoid reductionism to a single level of explanation, a relational perspective is necessary. This perspective emphasizes that description and multiple explanatory levels of analysis are complementary features of a complete explanation. Thus, any complete explanation may entail all levels, but no level represents a competing alternative to other levels. Within this context, we explore the advantages of this approach for executive function research, and conclude with suggestions uniting the levels into an integrated system of explanation.
