An issue of particular concern in mathematics teacher education is the relationship between theory and practice, and the nature of university–school partnerships. We report here on results from a research project answering the call for a more systematic understanding of the practice learning context. The study focuses on the new Norwegian elementary teacher education programme and highlights the difficulties involved in connecting theory and practice and how prospective teachers may be supported in this respect. Focus group interviews involving 51 first-year prospective teachers and 25 teacher–mentors investigated early school placements, specifically prospective teachers’ positions in the classroom as teachers of mathematics, and the ways in which the mentoring relationship supported their developing role. Taking a communities of practice perspective, we found that the idea of movement across intersecting and sometimes conflicting communities of practice is helpful in aiding our understanding of the difficulty of connecting theory and practice. Additionally, variations in mentoring styles and perceptions of prospective teachers’ mathematics and pedagogic knowledge competencies play a part in some prospective teachers’ difficulties in taking up a role as legitimate peripheral participant in the school. We conclude by considering ways in which prospective teachers might be better supported to cope with school placement.