The principles of content-based image retrieval (CBIR) are now well-established, with a continuing flow of publications exploring various aspects of the technology. Practical applications receive rather less attention and few fully-developed instances have been described. In this paper, we review the remarks made by other authors that led us to believe that it was important to investigate what users expect when using CBIR and how they react to the interface provided. We report the results of observing a number of subjects, with varying experience, while using a CBIR system to search for images. We interpret these observations and obtain insights into the role CBIR might play in meeting the challenge of image retrieval. The work is being carried out as part of the ELISE project (Electronic Library Image Service for Europe), which is partly funded by the European Commission under its Fourth Framework Libraries Programme.