Introduction: Globally , approximately 4.3% of children aged 0–4 years live with developmental disabilities. Integrating early detection within routine public health services enables timely referral and intervention, reducing long-term functional impairment. We describe the implementation of a district-level detection and care pathway for 36-month-old children in Colombo District, Sri Lanka. Objectives: To implement and evaluate a structured developmental detection and referral pathway at 36 months in Colombo District. Methods: Public Health Midwives (PHMs) were trained to conduct developmental surveillance using the Child Health Development Record (CHDR) based on parental report and observation. The Social Attention and Communication Surveillance – Preschool (SACS-PR) tool was incorporated to identify social-communication concerns. SACS-PR was translated into Sinhala and Tamil, back-translated, and culturally adapted according to WHO guidelines. Psychometric properties and interrater reliability were assessed following PHM training by a SACS master trainer. Screening was conducted among children aged 31–42 months between November 2024 and January 2026. Ethical approval was obtained from the Sri Lanka College of Paediatricians Ethics Review Committee. Results: A total of 1,294 children were screened. PHMs demonstrated good reliability in administering SACS-PR. The tool showed satisfactory psychometric properties for use as a secondary screening instrument for social-communication disorders, including autism.Developmental atypicalities were identified in a significant proportion of children using both CHDR and SACS- PR. Conclusions: Embedding structured developmental screening at 36 months is feasible withinroutine public health services. This pathway identified previously unrecognised developmental vulnerabilities and strengthened early referral and intervention within the public health system.