Supervision, as a research field, has received a considerable amount of attention within counselling psychology, social work and psychotherapy. Although there is no lack of theoretical writings on supervision within these disciplines, the theories themselves have provided little guidance for continuing research and practice. This has resulted in confusion concerning the purpose of supervision, its distinctiveness from other similar activities, the role and function of the respective participants in the process, and the tasks and methods to be employed. This paper, the first of three on the experience of supervision in occupational therapy, describes a grounded theory study which set out to investigate the processes underlying supervision in the discipline of occupational therapy from the perspective of the supervisor. The data were collected by interviewing 30 occupational therapy supervisors in the South West of England. The results suggest that supervision is frequently experienced as an uncomfortable and relatively unproductive process within this occupational group. In addition, the data lend support to the possible existence of an egalitarian relationship which operates between supervisor and supervisee, with associated payoffs and risks for each participant in the relationship. A second paper reporting the supervisee's perspective will be published as part 2, together with recommendations for future practice in part 3.