This work presents an account of research and development activities in open, distance and flexible learning. The use of open, distance and flexible learning materials is expanding dramatically, not just in schools, further and higher education but also in industry, commerce and the social services. Most higher-education institutions now have an open learning unit or educational development centre, and major organisations such as British Steel, National Westminster Bank, Leeds Building Society, Rover Cars and the Inland Revenue have formed units to develop teaching and training materials. Internationally, growth is even more impressive, with new Open Universities planned for Singapore, Bangladesh, South Africa and India, whilst those in Malaysia, Thailand and Australia continue to expand. But current and future practice must be based on research evidence rather than intuition.