Objectives (1) To test the validity and reliability(internal consistency and inter-rater reliability)of the new CHaT-3 in Chinese children in Hong Kong any items that can best discriminate the autistic development will be sought To determine the most suitable cut-off criteria and risk stratification from the graduated scores of chat-3Objectives (1) • To test the validity and reliability (internal consistency and inter-rater reliability) of the new CHAT-3 in Chinese children in Hong Kong • Any items that can best discriminate the autistic development will be sought • To determine the most suitable cut-off criteria and risk stratification from the graduated scores of CHAT-3