Preschool-age children who are experiencing delays in physical, cognitive, communication, social, emotional, or adaptive development are often referred for a comprehensive assessment to make diagnostic determinations and to help develop appropriate interventions. Typically cognitive assessment has a key role in a comprehensive evaluation of a young child. In this article, five individually administered tests of cognitive ability, normed for the preschool-age child, are reviewed. These specific tests include the "Bayley Scales of Infant Development", 2nd edition, the "Kaufman Assessment Battery for Children", 2nd edition, the "Wechsler Preschool and Primary Scale of Intelligence", 3rd edition, the "Stanford-Binet Intelligence Scale", 5th edition, and the "Differential Abilities Scales". The following is provided for these cognitive instruments: a description of the test procedures, information on scoring systems, highlights of the technical qualities, and a summary of the general meaning of test results. The article concludes with strengths and limitations of the instruments. (Contains 9 tables and 2 figures.)