Early identification of developmental disorders in children with special needs is critical for timely intervention and improved developmental outcomes. This study evaluated the psychometric properties of three commonly used developmental screening instruments (the Ages and Stages Questionnaire (ASQ), the Modified Checklist for Autism in Toddlers (M-CHAT), and the Denver Developmental Screening Test II (DDST-II)) to determine their reliability, validity, and diagnostic accuracy in a sample of 350 children aged 6–60 months. Data were collected from pediatric clinics and special education centers, with caregivers completing the ASQ and M-CHAT, while certified clinicians administered the DDST-II. Reliability was assessed using Cronbach’s alpha and test–retest correlations, validity was evaluated through construct and criterion-related analyses, and diagnostic accuracy was examined via sensitivity, specificity, and ROC analyses. Results indicated that the DDST-II demonstrated the highest reliability (α = .92; r = .90) and diagnostic accuracy (sensitivity = 89.2%; specificity = 85.5%), followed by the ASQ (α = .89; r = .86; sensitivity = 83.6%; specificity = 78.5%). The M-CHAT showed moderate reliability (α = .78; r = .80) and diagnostic accuracy (sensitivity = 76.3%; specificity = 73.4%). Construct validity analyses confirmed expected domain structures for the ASQ and DDST-II, while M-CHAT showed lower factorial congruence. Criterion-related validity was highest for the DDST-II (r = .85) and ASQ (r = .72), with a moderate association for M-CHAT (r = .66). These findings suggest that all three instruments are suitable for developmental screening in children with special needs, with the DDST-II providing superior diagnostic performance. The study reveals the importance of multi-method screening approaches, culturally sensitive validation, and structured follow-up for autism-specific measures. Recommendations include integrating routine developmental screening into public health programs, professional training for administrators, and further research to refine and adapt screening tools for diverse populations.