This chapter examines the relationship between workplace learning and Lave and Wenger's (1991) theory of Communities of Practice (CoPs). Drawing on research with schoolteachers, the chapter presents two case study accounts of two CoPs in two different French schools. It focuses on the practices of mathematics and science schoolteachers to support the development of their learning. Results suggest that exchange and interactions initiated in these communities converge into common purpose and lead the group members to reflective practice to improve and share their pedagogical practices or resolve their professional problems. Learning takes place by communication, criticism, dialogue, collaboration and can be supported by technology. This research attempts to show teachers that their own learning can be made more effective by linking the individual learning to collective or social learning.