An examination of the relationship between formulation and design. The main aspects of mathematical formulation are the development of definitions of variables and the functional relationships of the variables required to model the situation under study. The design of an efficient mathematical formulation is an activity analogous to other engineering design activities: it requires an intimate knowledge of the problem being studied and an ability to evolve novel approaches to the design. In this paper, the design aspects of mathematical formulation are discussed as follows: (1) statement of the problem to be formulated; (2) definitions and relationships for a first design; (3) redesign to reduce the number of unknowns, variables, and constraints; (4) refinement of the redesign; and (5) generalization to a multiproject scheduling problem. Despite complex symbolism, only algebraic manipulations are employed.