This study investigated the effects of participation levels (dose) on child development (response) in five school sites offering integrated early childhood services as part of the Toronto First Duty (TFD) demonstration project. The TFD model offered an integrated school-based service array for children under 6, including public school kindergarten, childcare, family literacy, parenting supports and other early childhood services. While investigating program dose effects, this study also considered the social ecology of the child, including family- and school-level characteristics that might alter the effectiveness of community-level service integration efforts to improve child development outcomes in kindergarten as children enter school. The ecology of participation effects was examined through generalized linear modeling techniques analyzing a linked dataset (N = 272) including intake data on family demographics and parents' goals on service use, systematic tracking data on hours of program use, service integration level data across school sites, and child development data across five domains on the Early Development Instrument (EDI). The results provide evidence that the early childhood integrated service model has potential to improve children's developmental outcomes: participation dose predicted children's physical health and well-being, language and cognitive development, and communication and general knowledge, after taking into account demographic, parent engagement and site factors. Parents' being less child-centered in their goals for service use and less interested in school involvement were significant risk factors associated with children's developmental outcomes. This study has implications for understanding the ecological complexities of early human development and integrated service supports in a school-as-hub model. (author abstract)