Understanding Developmental Coordination Disorder in Youth Functioning: Measurement Properties of the Spanish Adolescents and Adults Coordination Questionnaire

<b>Background/Objectives</b>: The Adolescent and Adult Coordination Questionnaire (AAC-Q) is a brief self-report tool developed to assess daily performance difficulties related to Criterion B of Developmental Coordination Disorder (DCD) across adolescence and adulthood. Despite the AAC-Q's clinical and research relevance, its psychometric properties have not yet been comprehensively evaluated. This study aimed to examine the structural, construct, and criterion validity, internal consistency, and test-retest reliability of the AAC-Q and to establish normative percentile bands for Spanish adolescents and young adults (AAC-Q-ES). <b>Methods</b>: A cross-sectional psychometric study was conducted in 800 typically developing participants (200 adolescents, 600 young adults). Measurement properties-including factor structure, internal consistency, test-retest reliability, construct validity, and criterion validity-were assessed following COSMIN guidelines. Percentile cut-offs were calculated for adolescents and young adults. <b>Results:</b> The AAC-Q-ES revealed a three-factor structure with excellent fit indices (CFI = 0.95-0.98; RMSEA = 0.060-0.067). Internal consistency was good (α = 0.76-0.83), and test-retest reliability was excellent (ICC = 0.90, <i>p</i> < 0.001). Criterion validity with the Adult DCD/Dyspraxia Checklist was very high in adults (r = 0.972, <i>p</i> < 0.001), and construct validity in adolescents was confirmed through moderate correlations with the Flamingo Balance Test (r = -0.352, <i>p</i> < 0.01). Age- and sex-specific percentile bands were established. <b>Conclusions:</b> The AAC-Q-ES is a psychometrically robust, culturally adapted, and efficient tool for assessing functional difficulties related to DCD in Spanish adolescents and young adults, facilitating both clinical and research applications.