A transformation of American education is underway. Blended and personalized learning is sweeping across the country in schools and districts of all types and sizes. This trend is breathtaking and tremendously exciting. One of the central elements of blended learning is mastery-based learning: enabling students to move forward in their learning at their own pace as they master content rather than based on traditional time structures. Schools and districts are starting to take tangible steps in this direction. However, software programs currently offered by the marketplace do not include the functionality necessary to make this possible in a way that leads to a scalable, inexpensive, long-term solution. Many learning systems include proprietary learning objectives, and most systems integrate the data about student progress in a way that impedes integration with other learning solutions. This is a gap in the blended learning ecosystem that must be addressed quickly. Without clear examples of how to bring blended learning to life in classrooms and realize the benefits for students and teachers, the success of the entire movement is in jeopardy. Over the past few years the MasteryTrack system has been developed to meet this need. It offers a structure for mastery-based learning that can be implemented immediately in classrooms and provides a compelling illustration of the kind of functionality required by the ecosystem.