The theories and results discussed in this article are from a study investigating the identity development of novice primary mathematics teachers. The article has two aims: first, to elaborate the notion of beliefs in relation to the notions of identity and identity development, with the purpose of developing a framework to investigate the process of becoming and being a teacher of mathematics; and second, to offer an example of the use of this framework in a study of novice primary mathematics teachers. The core of the example is the case of Jenny, a Swedish novice primary mathematics teacher. Jenny’s case, however, is not simply about her but also identity development when the formal aspect of employment is missing, a case not rare in Sweden.