Teacher professionalization is essentially a process, updating, innovation, specialization and contextualization. It aims at improving professional performance and transforming educational practice. The starting point for the development of professionalization is to identify the characteristics that a teacher should have according to the context of professional performance, always linked to the identification of the multiple and complex professional problems that are generated in the practical activity of the teacher. This book offers a theoretical analysis and an empirical evaluation of this process in the context of the Pre-university Vocational Institute of Exact Sciences in Cuba. It is the result of a project associated to the Sectorial Program "Cuban Educational System. Perspectives of development" of the Ministry of Education.