This article differentiates approaches to school-based teacher education. It contrasts the pervasive apprenticeship model, to a "naturally integrated" school-based teacher education program that we describe as a complex learning system. Rather than view teacher education as fragmented by separating educational theory (physically based on a university campus) and teaching practice (based in a school and resembling an apprenticeship), we favor an approach where all coursework is integrated with practice in a host school while maintaining close connections to the university. The latter model highlights learning as contextualized in school, focused on the whole school, yet also informed by progressive educational thought. All participants in the school environment (not just university students) are at once both learners and teachers.