This study examined the psychometric and technical characteristics of various measures of attention deficit hyperactivity disorder (ADHD) that are commonly used with preschool-aged children. Information on reliability, validity, norms, and scale-specific features was gathered from the test manuals of four commonly used behavior rating scales: (1) Early Childhood Attention Deficit Disorders Evaluation Scale (S. McCarney, 1995); (2) Behavior Assessment System for Children (C. Reynolds and R. Kamphaus, 1994); (3) Connors' Rating Scales-Revised (C. Connors, 1990); and (4) ADHD Rating Scale-IV (G. DuPaul, T. Power, A. Anastopoulous, and R. Reid, 1998). Although most of the test manuals reviewed provided sufficient evidence of reliability and validity for ages 5 and up, many did not provide sufficient detail about psychometric data from preschoolers. In many cases, psychometric information relevant to assessment with preschoolers was presented but was grouped with data from other age groups (e.g., ages 4-11). Furthermore, because the scales reviewed in this article differed in terms of various special features, such as validity scales and clinical norms, clinicians should carefully consider the match between the purposes of the assessment and the instrument used. (Contains 4 tables and 11 references.) (Author/SLD)