This paper aims to contribute to research and policy that supports Latino children in early education regarding their transition into the school system and their bilingual development. It presents the results of a one-year longitudinal ethnographic study of four Latino children starting school at a transitional bilingual kindergarten in the Boston area. The analysis identifies dynamics and trends at the micro and meso levels that show that Spanish use and development in Latino children cannot be fully understood and supported if we consider it an individual ability instead of an organic and intrinsic component of broader dynamic socialization, emotional, and academic processes (such as the transition to school) of which English is also a part and in which parents and teachers participate. Recommendations for designing and implementing comprehensive programs to engage Latino families and educators to support transitions, bilingual development, and academic performance in young Latino children are presented. (author abstract)