The research project has developed a design framework for an adaptive MOOC that complements the MOOC format with blended learning. The design framework consists of a design model and a series of learning design principles which can be used to design in-service courses for teacher professional development. The framework has been evaluated by alpha-testing and beta-testing, and the relationship between design principles and the intended, the implemented and the attained designs has been analyzed. The project is methodologically inspired by Design Based Research.