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

Background/Objectives: 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). Methods: 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. Results: 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, p < 0.001). Criterion validity with the Adult DCD/Dyspraxia Checklist was very high in adults (r = 0.972, p < 0.001), and construct validity in adolescents was confirmed through moderate correlations with the Flamingo Balance Test (r = −0.352, p < 0.01). Age- and sex-specific percentile bands were established. Conclusions: 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.