The German Centre for Mathematics Teacher Education (DZLM) together with the Ministry of Education is in charge of developing, delivering and evaluating a long-term continuing professional development program (CPD) with respect to graphics calculators (GC). In this paper we describe the design of the CPD program and two associated research studies. The studies aim at examining conditions which must be considered when designing a CPD program, and at investigating the effects caused by the CPD program on teachers’ beliefs and classroom practices as well as on students’ competencies. We developed a questionnaire to measure teachers’ beliefs related to GC and a survey about the integration of the GC into classroom practice. Furthermore, an achievement test was constructed to measure students’ competencies that focus on areas where the literature expects the GC to be relevant.