There is a need to balance the quality of professionally designed information systems with the end user’s current knowledge of specific decision contexts. This is particularly so for intelligent systems. This paper looks at some theoretical underpinnings for the potential end- user development of intelligent systems. General requirements are characterised and the metaphor of a semantic spreadsheet is introduced. A two level process enabling end user development of knowledge-based systems is described. The first involves the development of a design environment that allows experts to develop the knowledge base. The second involves development within the design environment for the ultimate end users.