Suggesting that a missing link between effective practices and their sustained implementation is the "host environment" into which practices, programs, procedures, and pedagogy are translated, this bulletin describes the need for prevention and intervention models in beginning reading that are anchored to the school as the host environment. The model is developed at the school-building level for a particular host environment and for the long term; anchored to ongoing student performance in priority subject areas; customized by collaborative grade-level teams to fit and take hold at the school-building level; and tethered to a centralized data-management system. The paper contains three major sections: (1) a conceptual framework for understanding and mapping the complex and multiple contexts of schools; (2) a set of "big ideas" for designing effective beginning reading instruction for students in kindergarten through grade 3; and (3) the features of a school-wide intervention model customized for beginning reading. Contains several unnumbered figures and 66 references. (RS)