A wing-design optimization study is conducted on a composite wing. The objective is to evaluate the effect of the compositelayup orientation on theoptimized weight while satisfying constraints on strength, roll-reversalvelocity, and e utter velocity. The wing optimization studies are presented with the composite layups oriented at 5-deg increments up to § 20 deg from the midspar of the wing. The multidisciplinary optimization system, ASTROS, was used in the design study. This study, although not conclusive, indicates that optimal designs when subjected to multiple structural constraints are relatively insensitive to the orientation of the laminate layup. I. Introduction M ULTIDISCIPLINARYdesign optimization (MDO)hasbeen the subject of numerous investigations in recent years. This technology push is primarily attributed to the rapid growth in speed, data transfer,and storage capabilities of modern computers. Itis anticipated that in a few years the speed of computation may surpass the Ge ops/s range with similar improvements in memory devices. The computer’ s capabilities are doubling or tripling in a relatively short time, while the cost of computation and information processing is reducing by similar factors. These far-reaching developments in computers are the propelling force behind the rapid evolution of the so-called information highway . The information explosion is already affecting almost every facet of life in industrialized countrieswhilepushing industrializationofthe remainingcountries.The world is a very competitive market place for products. It is expected to be even better for the consumer. Cost, quality, and innovation are the key ingredients for success in such an environment. A wellorchestrated MDO strategy is the best means for improvement in all three areas. It is often the mistakes made in early design that haunt the bad performance of the products. MDO systems on modern computers allow the rapid evaluation of the operation scenarios of the products. The rapid strides in computers are the catalyst in promoting sophisticated computer architectures, database technology, and numerical methods. These developments, in turn, are providing the necessary infrastructure for integration of both disciplines and the designstages.Forexample,inairframedevelopment,aerodynamics, structures, and controls are the main disciplines; whereas in design, manufacture, operation, and maintenance are the stages of development. Each of these stages is further divided into manageable tasks that are appropriate to available resources. For example, the design task is traditionally conducted in conceptual, preliminary, and detail design stages. If we couple this view of design with the task of integration of the disciplines (such as aerodynamics, structures, and controls ), we have an almost intractable optimization problem, where the overall minimum cost is the primary driver. It is under