Any system designed for people to use should be (a) easy to learn; (b) useful, i.e., contain functions people really need in their work; (c) easy to use; and (d) pleasant to use. In this note we present theoretical considerations and empirical data relevant to attaining these goals. First, we mention four principles for system design which we believe are necessary to attain these goals; Then we present survey results that demonstrate that our principles are not really all that obvious, but just seem obvious once presented. The responses of designers suggest they may sometimes think they are doing what we recommend when in fact they are not. This is consistent with the experience that systems designers do not often recommend or use them themselves. We contrast some of these responses with what we have in mind in order to provide a more useful description of our principles. Lastly, we consider why this might be so. These sections are summaries of those in a longer paper to appear elsewhere (Gould & Lewis, 1983). In that paper we elaborate on our four principles, showing how they form the basis for a general methodology of design, and we describe a successful example of using them in actual system design (IBM's Audio Distribution System).