Introduction: The purpose of this study was to develop and validate a diagnostic measure of attention deficit, hyperactivity disorder and impulsivity. Method: The instrument was administered to normal (n=51), learning disability (LD) (n=96) and intellectually disabled (ID) (n=108) children. The instrument in its final form comprises 36 items. Results: Reliability analysis, exploratory factor analysis, and confirmatory factor analysis revealed that the instrument possesses good reliability and validity estimates. MANOVA revealed that intellectually disabled, learning disabled and normal children differed significantly on all of the five subscales. The pattern of difference mainly favored I.D. children then L.D. The lowest scores on all of the subscales were those of the normal children. Discussion and Conclusion: It is important that children with L.D. be differentiated from other types of disabilities. The instrument at hand is presumed to make such distinction. Namely, the instrument is a tool to identify children with attention deficit and hyperactivity disorder. (Contains 1 figure and 3 tables.)