The purpose of this study was to develop a Korean infant-toddler developmental scale and to examine the demographic variables and infant-toddler development. The subjects were 167 mothers who have infant and toddler from 1 to 36 months of age in Seoul, Daejeon, Chungju, Yeasan, and llsan in Korea. The subscales consisted of language development, social and emotional development, physical development, and cognitive development. The significant variables which are influenced the infant-toddler development were age of infant-toddler and age of father.