Many Studies have indicated that the experiences of the first 3 years of life are far more important than we had previously thought. Although most of the early childhood programs have focused on the educational environment of 4 and 5 year olds, we should now turn our attention to the first 3 years in early childhood education. The purpose of this paper was to review theoretical and research foundations of infant and toddler programs, so as to provide the theoretical basis for program development. In order to develop a infant and toddler enrichment program in Korea, this paper has collected information about what, how, and where we can carry out programs during the very important first 3 years in order to develop the full range of early educational development. Further experiments are needed to differentiate the level of infants and toddlers from various cultural backgrounds, and to develop the various forms of infant and toddler enrichment programs.