ISIS is a multicomputer-based interactive system for the imaging of seismic reflection data. In the sense used here, interactive means that when the seismic analyst makes an adjustment to an imaging parameter, the displayed image is updated rapidly enough to create a feedback loop between the analyst and the imaging machine. This interactive responsiveness allows a much greater use of the analyst's talents and training than conventional seismic processing systems do. To carry out the interactive imaging, we introduce a set of conceptual tools for the analyst to exploit, and also suggest a new role for the structural geologist-who is usually charged with interpreting a seismic image-as geologist/analyst.