This paper describes the research strategies employed in the Dutch Technology Enriched Schools (TES) project, which was initiated in 1987 to introduce computers into secondary education, to encourage extensive and intensive use of computers in a small number of secondary schools, and to study the effects of computer use on the classroom, the curriculum, and school administration and management. The project, extending over a five-year period, involved three experimental schools that were equipped with a considerable amount of hardware and teacher facilities. The characteristics of the study highlighted in this paper are: (1) the case study approach; (2) emphasis on the need for cooperation between teachers and researchers; (3) the wide spectrum of effects being investigated; (4) the long-term character of the project; and (5) the generalizability of the findings. (ALF)