Variation in definitions and models of personalized learning has created confusion and disagreement among practitioners and scholars. However, personalized learning continues to be broadly promoted and funded within schools. This paper offers an inclusive definition of what is happening within the personalized learning movement and aims to be inclusive of diverse epistemologies and cultures. To do this, we revisit the seminal metaphor of the factory model of schooling and follow contemporary changes seen in manufacturing to highlight similar trajectories seen in both fields and justify this new definition, which states that personalized learning is the mass customization of learning through a unique combination of automated and student-centered pedagogies. We then propose the Personalized Learning Continuum Framework (PLCF) as a conceptual framework for this movement to help practitioners and researchers describe the relationships between various models as a function of Academic Learning Time, pedagogical methods founded on contrasting philosophical traditions, and the distribution of power in learning.