The goal of the present research is to describe five lower-secondary in-service mathematics teachers' development of ICT (Information Communication Tech-nology) integration in their teaching as a result of mentoring pre-service teachers who practiced the integration of technology in their mathematics teaching. This is done through the combination of Schoenfeld's Teaching-in-Context theory and Goos' community of practice framework. To collect the research data, the re-searchers used semi-structured interviews with the in-service teachers at the be-ginning and end of the academic year. In addition, several observations of lessons taught by the in-service teachers with the assist of pre-service teachers were rec-orded towards the end of the intervention. The research findings indicate that the community of practice context can serve as an escalator that supports the decision of in-service mathematics teachers to integrate ICT in their mathematics teaching. However, these decisions were conditioned by taking care of the students' formal procedural mathematical knowledge.