Executive function develops at an unprecedented rate during the preschool period, yet few clinicians attempt to assess executive processes in young children. The primary objective of this article is to demonstrate that executive function can be assessed in preschoolers, and to highlight the importance of detecting executive dysfunction as early as possible. Following a description of executive function and the underlying neural systems, this article outlines some of the challenges in assessing executive function in young children. The various assessment paradigms used for assessing executive function in preschoolers are presented, and based on studies that have applied these measurement tools normal development of executive domains is described. Finally, the benefits and opportunities for executive function intervention in the preschool period are considered.