Analytical target cascading is a relatively new methodology for the design of engineering systems. Analytical target cascading deals with the issue of propagating desirable top-level product-design specifications (or targets) to appropriate targets at lower levels in a consistent and efficient manner. Most existing problem formulations for multilevel design often exhibit convergence difficulties. It is proved that the analytical target cascading process converges to a point that satisfies the necessary optimality conditions of the original design target problem.