This chapter presents and analyzes current developments in the evolution of the instructional development model. First, basic definitions of general systems and instructional development model terms are provided, and the differing uses of the terms instructional development, instructional technology, and educational technology are considered. The idea of a model and four different ways in which to use this term are then discussed, as well as current and classic instructional development models. These instructional development models are analyzed and compared, and criteria for selecting a model for use in a specific project are given. Finally, a process for developing instructional development models is outlined, and areas of needed research are detailed. Six figures are provided. (68 references) (Author/EW)