Aydoner Bektas, SelenBumin, GoncaKarahan, Sevilay2026-05-122026-05-1220262162-29732162-296510.1080/21622965.2026.26401832-s2.0-105032129369https://hdl.handle.net/123456789/1484https://doi.org/10.1080/21622965.2026.2640183This study aimed to develop the Comprehensive School Readiness Assessment Scale (COSRAS), a multidimensional instrument designed to evaluate school readiness in children aged 57-72 months. Scale development followed DeVellis's framework. An initial item pool of 216 items was generated based on developmental, learning-related, and functional school readiness constructs and subsequently refined through expert review to 182 items. The finalized scale was completed by teachers of 1813 children, and test-retest reliability data were obtained from 386 teachers. Content validity indices were high, ranging from 0.892 to 1.000. Exploratory and confirmatory factor analyses supported the proposed eight-factor structure, demonstrating excellent model fit (CFI = 0.999; RMSEA = 0.000-0.009). Convergent validity with the Primary School Readiness Scale was strong (r = 0.665-0.695). The internal consistency of the scale was excellent across all domains (alpha = 0.916-0.969), and test-retest reliability was high (ICC > 0.990). COSRAS demonstrates strong psychometric properties and provides a comprehensive assessment of school readiness by integrating developmental competencies, learning-related skills, and functional performance. The scale enables early identification of children who may be at risk for neurodevelopmental or learning-related challenges before school entry. COSRAS may assist educators and allied professionals in early childhood and school-based settings by offering domain-specific profiles that inform instructional planning, individualized supports, and early intervention strategies.eninfo:eu-repo/semantics/closedAccessDevelopmental DomainsSchool ReadinessValidityEarly ChildhoodReliabilityArticle