Organized extracurricular activities (EAs) are an important component of the microsystem that impacts children's lives. Previous literature has primarily focused on school-aged children and youth in Western societies. This study utilized a longitudinal design and examined the antecedents and consequences of extracurricular participation in a sample of 194 Hong Kong Chinese preschoolers. The results showed that higher family socioeconomic status (SES) predicted higher levels of participation in EAs (e.g., attendance intensity and the breadth of participation). Children from higher-SES families were more likely to involve in non-academic-oriented EAs. Participation in EAs was generally associated with the growth trajectories of reading and math skills in children from less advantaged SES backgrounds, but not higher-SES children. In contrast, EA participation was not associated with children's social skills. Findings highlight the importance of examining the relationship between EA participation and children's early development in non-Western societies. Copyright ©Elsevier Ltd.