"Introducing and implementing CAS into pre- and in-service education and training" Yasar Ersoy Middle East Technical University (METU) Dept SSME, Middle East Technical Uni. 06531 Ankara Turkey E-mail:yersoy@tutor.fedu.metu.edu.tr Much attention has been directed at reforming school mathematics. Some projects in various countries are working on the integration and implementation of information technologies, namely computers and calculators, into school mathematics curricula and undergraduate courses in universities. The central theme of these projects is the use of technologies to enhance the learning of mathematics. Because, computer software tools such as computer algebra system (CAS) and graphical packages provide an ideal environment for student exploration of multiple representations, i.e. the connections between the visual/graphical representation and the analytical/algebraic one. In the present paper, we summarize our experiences in and issues on introducing and implementing information technologies, namely computers, CAS and TI-92 in the pre-service and in-service education and training of mathematics teachers in Turkey.