This book is based on the European Comenius project CROSSNET with eight case studies about innovation and science teacher education in six European countries. Guiding questions were how teachers, policy makers and teacher educators collaborate in the process of change and how local background projects respond to opportunities for the exchange of experiences and reflection in terms of a common theoretical framework of boundary crossing. The case studies were conducted by local coordinators and contracted teachers. They are supplemented by a cross-case analysis of common and distinct features in the projects and an essay about the relationship between boundary crossing, transformative learning and curriculum theory. Main outcomes are about school-based reform and collaboration for science education.