Computer based information systems are a pervasive part of work of a growing number of people. When new systems are introduced or the old ones changed the users must be trained to meet the new requirements. However, it is impossible to plan training before finding out the knowledge needs. Despite of their commonly accepted importance, competence issues have attained only modest attention by researchers and practitioners. In this paper we propose a conceptual model of the dimensions of the skill and knowledge needs of end-users. The model takes into consideration the content of the job (domain knowledge and tools), organisational aspects (own work and other’s work), and the differences of use situations (normal use, breakdown, and development)