This paper reviews four categories of models of motivational design, which is an aspect of instructional design that refers specifically to strategies, principles, and processes for making instruction appealing. Grounded in psychological theories of human behavior, the models in the first three categories discussed are based on person-centered theories, environmentally-centered theories, and interaction theories; the fourth group has a more pragmatic origin and includes omnibus models that incorporate both instructional design and motivational design strategies. Obstacles to motivational design are also discussed, including the unstable nature of motivation, which is related to the difficulties in establishing a useful theory of motivation; the multiplicity of motives and goal orientations of individuals; and the problem of measurement. A discussion of the growth and development of motivational design theory concludes the paper and 23 references are provided. (RP)