The aim of this article is to develop the foundations of a socio-cultural approach and to determine how this shapes our perception of a newcomer's construction of identity in two different workplaces: a high-technology delivery ward with newly employed midwives and a real estate agency with newly employed real estate agents. We explore how newcomers construct their identity through participation in different communities of practice at work and focus on what kind of learning processes the newcomer must be involved in and how they become involved. The construction of identity is seen as a mutual process between individual disposition (pre-existing identity) and the work structure. We find that initiative and the ability to act in anticipation of future problems or needs are decisive characteristics for how the newcomer learns, and that these are important for the creation of personal knowledge and for the ability to develop a new identity in a new profession.