Screening children at risk for developmental delay is very important in early intervention. Developmental screening test with solid validity and reliability is necessary for this work. Preschool Child Development Checklist (PCDC) and Screening Test of Comprehensive Developmental Inventory for Infant and Toddler (CDIIT-screen) are two tools widely used in Taiwan. The purpose of this study is to investigate the validity of the screening tests and referral standard of CDIIT-screen. Repeated measure research design was employed for the study. Six hundred and thirty eight infants and toddler participated this study. They were classified into 11 groups according to PCDC age level. The result revealed that CDIIT-screen held good construct validity. There were four reasonable referral standards for CDIIT-screen. The most appropriate standard was the child would be at risk for developmental delay if the z score of any one subtest of CDIIT-screen was less than or equal to -2. The PCDC is appropriate for infants aged under 1 year old. CDIIT-screen is recommended for children age older than 1 year old.
