Objective: This study evaluates the effectiveness of a center-based childcare program, namely, the stimulation, interaction, motivation, and experience (SIME) program for infants and toddlers. Method: Fifty-eight children between 1 and 2 years of age and their parents and childcare workers were recruited from two childcare centers in Hong Kong and participated in the SIME program over a 1-year period. Eighty-seven children from four other childcare centers served as controls. All children were grouped by age (1- vs. 2-year-old class). Results: The SIME program had positive effects on motor, language, cognitive and social development, parenting practices, and the quality of relationships with parents and childcare workers, especially for 1-year-old children and children from the center that served mainly families with a lower socioeconomic status (SES). Conclusion: The outcomes in 1-year-old children and children from the lower SES center confirm the success of this type of center-based infant-toddler program. (author abstract)