Until recently the great majority of instructional design (ID) models have relied on behavioral and information processing theories (Dick, 1996). There is, however, a growing body of literature on the practice of instructional design from a constructivist perspective (Winn, 1992). Much of this literature has emphasized the types of learning environments that can be developed such as anchored instruction or problem-based learning (Cognition and Technology Group at Vanderbilt, 1993; Wilson, 1996; Lin, Bransford, Hmelo, Kantor, Hickey, Secules, Petrosino, Goldman, and the Cognition and Technology Group at Vanderbilt, 1995; Reigeluth, 1996, 1997). In 1995 I described the first version of an instructional design model based on constructivist instructional and learning theories and an interpretivist philosophy of science (Willis, 1995). It was developed during work at NASA’s Johnson Space Center in Houston and at the Center for Information Technology in Education at the University of Houston. The model, named Recursive and Reflective Design and Development (R2D2), was one of the first to lay out in some detail an approach to creating instructional material that was based on constructivist theory. This paper, which is based on work at Iowa State University, describes a revision of the R2D2 model and discuss some of the practical issues involved in using an ID model.