Information retrieval access research is based on evaluation as the main vehicle of research: benchmarking procedures are regularly pursued by all contributors to the field. But benchmarking is only one half of evaluation: to validate the results the evaluation must include the study of user behaviour while performing tasks for which the system under consideration is intended. Designing and performing such studies systematically on research systems is a challenge, breaking the mould on how benchmarking evaluation can be performed and how results can be perceived. This is the research question of interactive information retrieval. The question of evaluation has also come to the fore through application moving from exclusively treating topic-oriented text to including other media, most notably images. This development challenges many of the underlying assumptions of topical text retrieval, and requires new evaluation frameworks, not unrelated to the questions raised by interactive study. This chapter describes how the interactive track of the Cross-Language Evaluation Forum (iCLEF) has addressed some of those theoretical and practical challenges.