In this paper we describe how techniques from psychology and knowledge engineering are used in forming a conceptual model of the musical composition process. The research in compositional processes which is described is based on research in design processes in different domains: written, architectural, industrial and musical composition. Experiments are conducted in which designers, in this case composers, are observed and recorded when performing their tasks. Recorded observations, including auditory, visual and spoken data, are analyzed afterwards. A model of the composition process derived from research in the above design domains can and will be refined and used in developing computer aided compositional tools in further research. These tools will not be mere “type-setting and printing” aids, as are many of the computer-based tools used nowadays, but will assist the process of musical composition itself. Tools can be automated, as in computer programs, or non-automated, as in a description of a new design environment