This article reports on how a program based on educative supervision supported the supervisory knowledge and practices of three cooperating teachers. The program was planned as a kind of practicum: the cooperating teachers participated in the program while working with a student teacher. The program included activities where the cooperating teachers reflected on their supervisory beliefs and practices in collaboration with each other. The case study method was used, where the case was the designed program. Data analysis indicated some changes in the supervision styles of the participating cooperating teachers toward educative supervision. First, the percent of speech given by the student teachers in the post-lesson conferences increased after the discussion of educative supervision in the program. Secondly, the amount and depth of talks on mathematics pedagogy increased. Thirdly, the cooperating teachers moved away from conveying their feedback directly to the student teachers; they started asking more open-ended questions to have the student teachers reflect on their teaching.