This paper reports on the findings of a larger case study that attempts to describe how people organize documents in their own offices. In that study, several dimensions along which people make classificatory decisions were identified. Of these, the use of to which a document is put emerged as a strong determiner of that document’s classification. The method of analysis is reviewed, and examples of the different kinds of uses are presented, demonstrating that it is possible to describe a wide variety of specific instances using a closed set of descriptors. The suggestion is made that, in designing systems for organizing materials, it might be advantageous to incorporate information about contextual variables, such as use, since these seem to be particularly important in classification decisions made within personal environments.