The Researching Effective CPD in Mathematics Education (RECME) project was set up under the auspices of the National Centre for Excellence in the Teaching of Mathematics (NCETM). The project aimed to: • characterise different types of continuing professional development (CPD) for teachers of mathematics (to include both formal and informal experiences); • investigate the interrelated factors that contribute to effective professional development for teachers of mathematics; • investigate evidence of effective professional development for teachers of mathematics; • establish the roles of research in professional development for teachers of mathematics. The study investigated 30 initiatives representing different models of professional development for teachers of mathematics, in different locations of England, taking place in the academic year 2007/2008. Overall, about 250 teachers in pre-primary, primary, secondary, further and adult education settings were involved in these initiatives. The study investigated the organisation of the professional development initiative. Two ‘focus teachers’ from each initiative were interviewed and observed in their classrooms.