Philosophiae Doctor - PhD / The research was prompted by two main issues prevalent in South African education in the last decade. These were particularly the critical state of the schooling system, especially in the educationally disadvantaged schools (mainly ex-Department of Education and Training) and the relationship of the teacher to teaching and the related issue of teacher upgrading. The resultant effect was that the educationally disadvantaged communities became more and more disadvantaged over time because of decreasing mental stimulation and mental development. The answer lay in finding a theory of intellectual growth and development which takes into account the learning environment of the disadvantaged child. The Educational Support Services Trust (ESST) has been active in addressing this very issue since 1986. It provides appropriate learner-centred mediational texts to disadvantaged pupils around the country. These materials concentrate on the development of practical intelligence by relating leaming to everyday experience. The Teachers' Methodology Project was designed to change the teachers who were using the ESST materials from being disseminators of information to being managers of a learning-centred classroom environment. The idea was to change the way that teachers thought about teaching and learning. This was accomplished by sharing the methodology of the existing pupils' materials and theories of cognition and mediation with them so that they could become adept at mediating at the level of deconstruction of complex ideas and using this knowledge in the construction and development of their own learning materials, thereby contributing to the mental development of their pupils. My experience as a staff member of the ESST and my background in education provided an entry point to this research via Feuerstein et at's (1980,1991) criteria for mediation, Haywood's (1993) mediational teaching style and a range of other theories and ideas including group work and co-operative learning, graphic organisers, and the ESSTs own theory of mediatory text (Sinclair, 1991). These were consolidated into a learning-centred approach to teaching in which the learner, the teacher and the task become part of the total learning-centred environment. The research began as an investigation of the Teachers' Methdology Project (TMP) and an effort to track teachers' development but grew to include the development of the conceptual mediational framework on which the project was based. This resulted in the development of a classroom observation instrument which was used to evaluate how teachers mediated in their classrooms and how they interacted with pupils. The TMP was implemented through a series of workshops during which teachers examined their assumptions about teaching and learning: explored new avenues for facilitating learning; experienced a learning-centred approach to teaching; acquired new strategies for and knowledge of, theories and atttitudes to teaching and learning and were able to reflect on and practise newly acquired skills in a supportive collegial environment. The research employed a qualitative approach and therefore the documentation of the process took considerable effort. An experiential framework (Kolb, 1974) was used to analyse the process and the results. This mediational experiential framework resulted in a methodology which addressed teachers' attitudes and cognition in a life-related way, taking into account their personal knowledge and experience. The methodology is replicable and has been used in basic adult education and other settings. In addition, the methodology can contribute to the understanding of how Outcomes-based Education could be implemented in South Africa.