The purpose of this paper is the investigation of the prevailing forms of in-service training, the detection of the dominant pedagogical discourse they promote as well as their contribution to the shaping of the teacher's individual theory of education (I.T.E.). The research was conducted using semi-structured interviews with a sample of 11 teachers who work in schools in Patras and the data were analysed using B. Bernstein's theoretical framework. The results of the research revealed that in our case, the predominant form of in-service training is the lecture, while the scientific knowledge provided refers to the content and teaching of cognitive subjects, the diagnosis and handling of learning difficulties and the acquisition of skills in the use of teaching aids. It also became clear that the I.T.E. of the teachers who participated in the research is chiefly shaped by elements of the professional biography of each teacher, in which in-service training does not seem to hold a dominant position.