The paper focuses on the contribution of action research to teachers‘ in-service education at elementary schools in the Rio de Janeiro local system of education, linking thought and action indissolubly. This involves inviting teachers and learners to question their own practice, in their own process of building up citizenship, while striving to recover their place in a society that limits and makes their social relations difficult. The development of action research at the Faculty of Education in Rio de Janeiro State University, Rio de Janeiro, Brazil, has brought to light ethical, scientific and political questions in the school system. [ABSTRACT FROM AUTHOR]