This article describes the evolution, over a 12-year period, of a telecollaborative project between two universities. The project focused on two teacher training courses that integrate in-class dialogic learning and flipped classroom materials. The authors begin by outlining the first years of the project, including an overview of the initial results concerning the student-teachers' progress towards professional teacher knowledge. Then, following the KARDS model for teacher education, the authors discuss the most recent year in which the use of telecollaboration with flipped class materials has been the foundation of the shared course, with the framework of the interaction based on the accumulated experience and knowledge gained over this long-term collaboration. The evolution of this telecollaboration reflects both a notable change in the mindset of the teachers as well as a deeper sense of responsibility from the students for their own learning.