Formulating design guidelines from research results can potentially offer two advantages: available empirical knowledge is distilled into a readily accessible form, and practitioners can judge the authority of those guidelines for themselves, but a case history demonstrates that challenges confront the developer of research-based guidelines for Web site design, First, few studies of people using the Web have yet been conducted. Second, when the process of guideline development is not systematic and designed to control bias and subjectivity, the resulting guidelines can be compromised. This paper describes the issues and problems that one guideline developer encountered and suggests a guideline development process that might resolve them.