SummarySchool innovating involves risks for teachers; professional risks, but also personal risks. So, the implantation and the diffusion of schools innovations are only possible if certain facilitating conditions are fulfilled.Considering a specific innovation developed for 15 years in Belgium (peer‐tutoring), the authors are trying to answer the following questions: •What conditions have to be fulfilled for an innovation to take shape and to expand?•What are the most important factors which determine the success or the failure of an innovation?•Even though the effects on pupils remain the justification of an innovation, how can we take into account the questions the teachers ask themselves at the different stages of the innovation? What are those questions? How can all the actors of the project find what they expected?