This paper discusses the findings of two empirical studies which investigated how students of English used two English learners’ dictionaries on CD-ROM. The outcome of these studies will indicate in what way such dictionaries can serve as reference and language learning tools. It is argued that an English learner’s dictionary on CD-ROM could be much more than an ‘ordinary’ reference work because it includes facilities that are not available in book form, such as audio and visual elements, exercises and games. The studies suggest, however, that a number of changes in content and design will have to be made in order to make such dictionaries more effective and beneficial to their users. Learners, on the other hand, may need to acquire special skills in order to benefit from all the information an English learner’s dictionary on CD-ROM contains.