Using an interpretative approach to teacher socialisation as a theoretical framework (Achinstein, Ogawa, & Speiglman, 2004; Kelchtermans & Ballet, 2002), this paper examines the ways in which student teachers’ and novice teachers’ job motivation (as part of their professional identity or self-understanding, Kelchtermans, 1993; 2009) is shaped by their professional contexts. A qualitative–interpretative methodology (multiple case study) was adopted. The choice of the 12 cases was made on conceptual grounds (theoretical sampling, Strauss & Corbin, 1998). We used a follow-up design. Data were collected using semi-structured interviews at two points in time: shortly before graduation from a three-year secondary education bachelor programme (Flanders, Belgium), and after one semester as beginning teachers. Data were analyzed using the method of constant comparative analysis (Strauss & Corbin, 1998). The focus of data collection/analysis was to reconstruct the development of job motivation and to identify the factors determining this process. Interpretative data analysis reveals that powerful sources of the development in job motivation concern events and interactions in which the ‘self’ as teacher was at stake. These mainly involve teachers’ need to develop a socially recognized sense of professional competence as well as their dealing with social and cultural working conditions in schools.