Material and Method: Ramathibodi Language Development (RLD) questionnaire was developed and completed by groups of 40 typically developing children age 18 to 30 months old and 30 children with delayed language development.

Results: The mean score was significantly lower in the delay language group (6.7±1.9), comparing with the typically developing group (9.6±0.7). The optimal ROC curve cut-off score was 8 with corresponding sensitivity and specificity were 98% and 72%, respectively. The corresponding area under the curve was 0.96 (95% CI = 0.92-0.99).

Conclusion: The RLD questionnaire was the promising language developmental screening instrument that easily utilized in well-child examination settings.

Keywords: Children, Language development, Questionnaire, Screening