Attributes of multimedia learning resources are explored, considering the physical resources, the learners, and the instructional design factors that appear to be crucial in determining interactive capability and potential for instruction. The first significant dimension that is discussed is the sensory dimension, which includes structural media attributes and also incorporates the imposed communication variable, message treatment. A processing dimension is discussed, which relates more closely to the functional attributes of media, and is approached from the viewpoint of what the learner brings to the media. A control dimension is also introduced, represented by a continuum from total control exercised by the program designed to the ability of the learner to manage the learning situation completely free of program control. Inquiry in these areas of education and instructional technology has the potential for being translated into practical guidelines for multimedia development. Two figures illustrate the discussion. (Contains 46 references.) (SLD)