Abstract
Objective: The Developmental Indicators for Assessment of Learning-Fourth Edition (DIAL-4) is a widely used screening tool grounded in developmental theory, designed to identify potential delays across motor, language, conceptual, self-help, and socio-emotional domains prior to school entry. While the DIAL-4 has been standardized in several countries, its norms may not fully capture the cultural, linguistic, and environmental characteristics that shape developmental trajectories of Iranian children. To address this gap, the present study aimed to establish culturally appropriate norms for the DIAL-4 in Iran, providing a valid and reliable framework for early identification and intervention. Method : This cross-sectional study standardized the Developmental Indicators for Assessment of Learning-Fourth Edition (DIAL-4) for Iranian children aged 2 years 6 months to 5 years 11 months. Districts in both cities were first selected using cluster sampling, considering socioeconomic and cultural diversity. Within these districts, kindergartens were randomly chosen. The final sample comprised 678 children. Trained examiners administered the Persian version of DIAL-4 individually. Raw scores on motor, concepts, and language subscales were converted into standardized developmental scores (M (=) 100, SD (=) 15), following established psychometric guidelines to generate culturally appropriate norms. Results: The findings indicated that the motor, concepts, and language subscales differed significantly across age groups (p < 0.05). Based on standardized scoring criteria, values below 70 were classified as indicative of severe deficits or developmental delays, scores between 70 and 84 reflected mild delays, scores from 85 to 115 were considered within the normative range, scores between 115 and 129 indicated above-average performance, and scores of 130 or higher represented an advanced level of functioning. When comparing the standardized developmental scores of Iranian children with those of American children, the results demonstrated that Iranian children consistently obtained lower scores across all three subscales. Conclusion: This study confirmed the suitability of the DIAL-4 for Iranian children and showed significant differences in motor, concepts, and language skills across age groups. Iranian children scored lower than American children on all subscales, highlighting the need for culturally specific norms to ensure accurate developmental assessment.