This paper seeks to establish evaluation as an important concern in hypermedia research and development, and presents a review of current hypermedia evaluation research with a prescriptive focus. Characteristics of hypermedia currently attracting the attention of instructional developers are discussed and conclusions drawn from recent evaluation research are presented along with distinguishing features that separate the evaluation approaches employed. Characteristics of hypermedia that present challenges to evaluative studies are analyzed and possible methodological solutions are suggested. Current and proposed activities at Lehigh University (Pennsylvania) which seek to apply the ideas presented in this paper to the development of hypermedia applications for technology transfer and training in engineering and other areas are also described. It is concluded that hypermedia requires an adaptive interactive research model to investigate the effects of treatment, and that this model will probably incorporate elements of both rationalistic and naturalistic approaches. Two figures show a comparison of rationalistic and naturalistic methodologies and the relationship between learner control and self-regulation. Three tables display the characteristics of hypermedia and expected outcome; selected evaluation research studies; and criteria for judging the trustworthiness of the findings of an evaluation study. (50 references) (BBM)