In order for automated information systems to be used effectively, they must be made easily accessible to a wide range of users and with short training periods. This work proposes a method of organizing documents based on the concepts of aggregation and generalization hierarchies. We propose a graphical user interface to provide a more intuitive form of Boolean query. This design is based on mapping the nodes of the aggregation hierarchy to Boolean union operations, and providing a concrete, graphical , manipulable representation of both of these node types. Finally, a working prototype interface is constructed and evaluated experimentally against a classical command-line Boolean query interface. In this experimental study, the graphical interface sh ows less than one-tenth of the error rate of the textual interface, on average. No significant differences in time spent specifying queries are found between the two interface types.