Computers and calculators are in general widely used in Norwegian schools, but with limited use in specific school subjects, as particularly in mathematics teaching. Various reports from surveys and research projects indicate that teachers' competence with ICT is a crucial point, and that teachers' lack of knowledge of how to utilise software for mathematics is a key challenge for further development. In the project ICT and mathematics learning (ICTML) at the University of Agder, the aim was to support the development of teachers' competence with ICT in order to improve mathematics teaching, learning, and problem solving with ICT. The theoretical framework is a socio-cultural view of learning and the concept inquiry community. The project applies a developmental research methodology implementing an inquiry cycle in which teachers and didacticians collaborate in developing teaching and learning of mathematics with ICT and build understanding and competence with ICT for mathematics. In this article, I will present fundamental ideas of the project together with evidence from collaboration in inquiry communities with teachers and didacticians and characteristic features of activities in workshops and classrooms. The working model has proved to support and strengthen development, but development of teaching takes a long time. (Contains 2 figures.)