Thesis Statement The thesis argument is that theory can be developed about the implementation, maintenance and dissemination of school health education based on a school development approach. Such theory development can assist teachers to design programs appropriate to the needs of their classrooms, schools and communities. Thesis Setting The implementation and maintenance of school health education programs has not usually been the focus of research and as a consequence is rarely reported in the literature. The research in this thesis draws upon many disciplines and fields but in order to answer the thesis questions methodological processes were required that were consistent with current school situations. The earlier School Development in Health Education (SDHE) program's work in research, development and dissemination provided the setting for the thesis. Methodology of the Research The methodology of the research study involved a case study approach using both multiple and single case studies. Data have been drawn from SDHE schools in South Australia undertaking health, sexuality and drug education. The methodology adopted for the studies in this thesis is a case study design incorporating an iterative theory-study-theory sequence in which an initial theory statement derived from the literature guides the development of a multiple case study which, in effect, 'tests' the theory in a qualitative way. The finding of the case study then informs development and elaboration of the theory statement in its second version. This is then used to test the next multiple case study which leads to further development of the theory in its third version. The third iteration of the theory is tested in a single case study that leads to the fourth and final version of the theory. Data analysis was aided by the use of the Q.S.R. NUD.IST computer package that helped to manage and explore the thesis ideas about the data. In establishing these syntheses the chain of evidence in the data sets was maintained. The analysis also allowed the thesis findings to be used to test theories about the data that answered the thesis questions. Thesis Findings The findings of the thesis are contained in the final version of the theory. The theory is structured around program drivers, phases, types and processes that together produce implementation, maintenance and dissemination. This final theory statement is the basis for drawing the thesis conclusions. Thesis Conclusions It was concluded that patterns of factors that enhance and inhibit the implementation, maintenance and dissemination of school health education programs could be placed in a theoretical framework that can guide practice in school health education. To be successful school health education programs have to include three critical elements: leadership, action research and funding. Leaders or program drivers need to be identified and resourced; they may be principals or designated teaching staff with access to decision making, policy processes and resource allocation in schools. Teachers need to engage in a reflective action research process to develop, modify and sustain their curriculum development work. Programs require adequate funding resources for teachers' professional development, including action research, and the purchase of human and material resources. Schools planning to introduce programs may learn from the experience of others but they must themselves engage in the critical and essential program features identified in the final version of the theory. Implications The thesis conclusions imply the need to use more efficient ways of bringing schools' and teachers' hidden competence to the fore to support school health education program through varied patterns of professional development, technical support and curriculum development and implementation, and through funding of enhanced professional practice for health literacy. A major implication for the health sector is that many health workers need to learn collaborative skills since there is a tendency to take control and attempt to direct what teachers should do rather than work with and support them. An implication for programs in complex social environments is the need for careful planning in collaboration with other stakeholders. The critical elements developed in this thesis also apply - leadership, action research and funding. Evaluation can adopt a case study approach as a more suitable method for examining what happens in programs than an overly simplistic approach of assessing goals and objectives which ignores the differences in program implementation for different sites with the necessary localisation. Further Research Further research suggested by the thesis findings are in the areas of school health education in the changing administrative and management environment today, and of the use of various types of case study research in tandem to answer comprehensive and complex program performance questions.