Test review: Delis-Kaplan executive function system.

The Delis-Kaplan Executive Function System (D-KEFS; Delis, Kaplan, & Kramer, 2001) represents the first set of executive tests co-normed on a large and representative national sample designed exclusively for the assessment of executive functions including flexibility of thinking, inhibition, problem solving, planning, impulse control, concept formation, abstract thinking, and creativity. The D-KEFS, composed of nine stand alone tests that can be individually or group administered, provides a standardized assessment of executive functions in children and adults between the ages of 8 and 89. Utilizing a "cognitive-process approach," the D-KEFS tests allow examiners to systematically generate and evaluate relevant clinical hypotheses on executive functioning of a given examinee by comparing and contrasting performance on multiple testing conditions and using contrast measure scores and error analyses. A review of the administration, scoring and interpretation, test construction, standardization, and technical adequacy indicate that the D-KEFS holds much promise not only as a clinical instrument, but also as a research tool for increasing knowledge of the frontal-lobe functions.