This study investigated the effects of participation levels (dose) on child development (response) infive 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 childrenunder 6, including public school kindergarten, childcare, family literacy, parenting supports and otherearly childhood services. While investigating program dose effects, this study also considered the socialecology of the child, including family- and school-level characteristics that might alter the effectivenessof community-level service integration efforts to improve child development outcomes in kindergartenas children enter school. The ecology of participation effects was examined through generalized linearmodeling techniques analyzing a linked dataset (N = 272) including intake data on family demographicsand parents’ goals on service use, systematic tracking data on hours of program use, service integrationlevel data across school sites, and child development data across five domains on the Early Develop-ment Instrument (EDI). The results provide evidence that the early childhood integrated service modelhas potential to improve children’s developmental outcomes: participation dose predicted children’sphysical health and well-being, language and cognitive development, and communication and generalknowledge, after taking into account demographic, parent engagement and site factors. Parents’ beingless child-centered in their goals for service use and less interested in school involvement were signif-icant risk factors associated with children’s developmental outcomes. This study has implications forunderstanding the ecological complexities of early human development and integrated service supportsin a school-as-hub model.