This document presents a study of graduates in Pedagogy and Biology with a focus on representations of the teaching profession. The analysis of the initial training and professional practice in the early years of career sought to highlight the point of view of these teachers in the construction of their professional identity. In times of changes in the structure and functioning of education systems, and the role of teachers, it is necessary to tighten the motivations, dispositions and values expressed by those who are part of this field. The polysemy of theoretical concepts and their interfaces are discussed in order to identify the teaching specificities as an activity in the process of professionalization, and to recognize the numerous influences that lead someone to become a teacher. The empirical material was produced by 195 questionnaires filled by graduates, formed from 2008 to 2015. The analytical categories used were beginning teachers, professionality, professionalization, and teaching work. According to these teachers, excessive theorizing and lack of practical approaches of teaching duties in the initial training makes it insufficient, and generates insecurity and the clash of expectations with the real world of work. There is a recognition of increasing requirements for the performance of teachers, although they do not participate in the instances of profession regulation and control. Added to this, the precarious conditions, lack of social prestige, and the effects of personal accountability on efficiency at work are the challenges for socialization and professional development of teachers.