This paper refers to a six-year research, which is still in progress (1996-2003), conducted by a public university in partnership with an elementary public school, both from the city of Sao Carlos/SP/Brazil. Aiming the promotion and investigation of teachers' professional development processes the research's chief concerns are expressed through the following question: To what extent a partnership process that considers reflection on the pedagogical practice as its axis of development and implies intervention/action of constructive-collaborative nature in the workplace allows us to know, understand and promote the professional development processes of schoolteachers? The research's main goals, are to: acquire knowledge about the professional development of teachers and the best way to investigate such issue; acquire knowledge about the process of conceptual development and about practices made possible by the use of a constructive-collaborative approach, and promote the professional development of teachers by means of reflection on the pedagogical action according to the assumptions of a constructive-collaborative approach, centered in the school. The adopted theoretical and methodological frameworks were drawn from literature regarding: teachers' professional development processes; teachers' thinking; inquiry and collaboration; communities of learning; models of knowledge base for teaching and the pedagogical reasoning process; reflection considered as a conceptual orientation; learning-in-context theory and organizational learning. The participants form a group of 23 professionals from an elementary school and 5 researchers from the university. The investigation contains elements of action-research, in the understanding of action oriented by research, and research based on action, reflection, decision-making processes, and on self-evaluation. Reflecting the theoretical orientation, the methodological approach includes descriptive and analytical studies follow up studies, ethnographic studies, case studies, and the use of several data sources (participant observation, diary entries, interviews, document analysis etc.), pertinent to each of the issues studied. Focusing problems and dilemmas faced daily by the schoolteachers the interventions (labeled by the participants as 'teaching and learning experiences') addressed many issues involving different ways of investigating and promoting professional development. General results: the schoolteachers considered the construction of pedagogical content knowledge as the most important element necessary for 'learning to teach'; the professional dimension of the schoolteachers' and the knowledge base for teaching they have adopted are grounded in the content areas of Portuguese and Mathematics, even when the teachers themselves presented difficulties to master such contents; there are hints of the existence of different levels/types of knowledge, suggesting that the axes/continua identified may be interpreted considering reflection as conceptual orientation; the teaching and learning processes observed were not linear, continuous, uniform and predictable. Achievements were slow, and fruit of arduous and systematic investment, calling for the creation of a common space for discussion and collective construction. The experiences did not affect all the teachers with the same intensity, nor can it be said that they have broken with the different types of resistance presented. The 'teaching and learning experiences' became important 'learning to teach' and professional development tools, offering all of the project participants concrete situations on which their different types of knowledge could be triggered and related. Their doubts were highlighted, their certainties put to proof, and their implicit theories challenged. By using these experiences as a starting point, it was possible to: analyze the teachers at different stages of their pedagogical practices; understand specific learning by the teachers in specific contexts that challenged them to reflect, verbalize their beliefs, and describe their practices; construct situations of reflection-on-action with narratives that made beliefs, values, and knowledge evident; visualize everyday school situations that require decision making, interpretation, evaluation, and the elaboration of new plans of action from the teachers, access (in a non-intrusive way) the classroom processes effectively developed by the teachers.