This thesis examines the relationship between distance education, adult learning and professional development for special education in the context of teachers' work with pupils with speech and language difficulties. Responses from students and tutors in three cohorts of a distance education course for teachers of pupils with speech and language difficulties are analysed and conclusions drawn concerning future practice in the light of changing professional needs. Qualitative methods, using questionnaires, interviews and systemic thinking activities, generate data for the analysis of course process in relation to student support, content and impact on practice. The study proposes a socio-technical systems model for planning, management and evaluation of professional development by distance education. This approach recognises that specific technical and organisational characteristics will interact with social and psychological aspects of participants' personal and professional lives.