Task instruction may be presented in many forms. However, training system designers are often forced to depend on intuition when choosing a presentation medium. Though past research has investigated the effectiveness of instructional media types, results have been mixed with no clear recommendations of which medium to use for instruction. An organizational framework for matching the appropriate medium or media to a learning situation is necessary for progress to occur in this research area. Through three experiments, we investigated the attributes of audio and video as instructional media, identified tasks for which we might predict the most beneficial instructional media, and tested our proposed organizational framework by manipulating the difficulty of the task and the complexity of the instructions. Older and younger adults participated in the experiments to help us understand differences in training needs for varying cognitive and perceptual abilities. We provide the basis for a taxonomy of instructional media and task demands, to be added through further research. (Contains 5 tables and 3 figures.) [Funding for this research was provided by the auspices of the Center for Research and Education on Aging and Technology Enhancement (CREATE).]