One-size-fits-all educational innovations do not work because they ignore contextual factors that determine an intervention's efficacy in a particular local situation. This paper presents a framework on how to design educational innovations for scalability through enhancing their adaptability for effective usage in a wide variety of settings. The River City multi-user virtual environment (MUVE), a technology-based curriculum designed to enhance engagement and learning in middle school science, is presented as a case study. To date over 250 teachers and 15,000 students throughout the United States and Canada have participated in the River City curriculum. Designers creating and evolving interventions can use this scaling framework to help them increase effectiveness, sustainability, and spread.