This digest, based on "Survey of Instructional Development Models," 3rd edition, defines instructional development (ID) in terms of four major activities: analysis of the setting and learner needs; design of a set of specifications for an effective, efficient, and relevant learner environment; development of all learner and management materials; and evaluation of the results of the development both formatively and summatively. A taxonomy of ID models can help clarify the underlying assumptions of each model, and help identify the conditions under which each might be most appropriately applied. The taxonomy has three categories indicating whether the model is best applied for developing: individual classroom instruction; products for implementation by users other than the developers; or large and complex instructional systems directed at an organization's problems or goals. Numerous ID models are mentioned for each of the three categories in the taxonomy. Gustafson and Branch suggest that developers need to acquire a working knowledge of several instructional development models, and ensure that all three categories in their taxonomy are represented in that knowledge. They believe that all the instructional development models they discussed will survive well into the next century, and will be able to accommodate new developments in theory and technology. (Contains 14 references.) (SWC)