- Objective: This article describes the development of a brief, ecologically valid, self-report questionnaire, the Adolescents and Adults Coordination Questionnaire (AAC-Q), used to identify developmental coordination disorder (DCD) in adolescents and adults. Method: The AAC-Q was completed by 28 adolescents and adults with suspected DCD ages 16-35 yr (mean [M] age = 21.18 yr) and 28 peers without DCD (M age = 27.64 yr). Cutoff scores for suspected DCD were established using data from a sample of 2,379 participants ages 19-25 yr (M age = 20.68 yr). Results: Reliability of the AAC-Q was determined using Cronbach's α (α = .88) and test-retest reliability (r = .94, p < .001). Independent-sample t tests to assess construct validity revealed significant differences between participants with and without DCD, t(27) = 9.37, p < .001. Conclusion: The AAC-Q is a standardized, reliable, and valid tool with potential for both research and clinical use.