At present, there is no preliminary design software that integrates damage tolerance with the other disciplines (i.e., strength, stiffness, aeroelastic response, etc.) which impact the design of an aircraft structure. As a result, the design of an aircraft structure that satisfies damage tolerance requirements, in addition to those of other disciplines, is presently accomplished via a manual ""cut and try"" procedure. This type of design process is time consuming and therefore very costly. To address this deficiency in existing software, a damage tolerance module is being implemented into the multi-disciplinary analysis and design software, ASTROS (Automated STRuctural Optimization System). The damage scenarios that are being considered in the damage tolerance module are applicable to the design of metallic and composite structure. The scenarios are: (1) single or multiple skin cracks (Widespread Fatigue Damage) in a stiffened structure, including the effect of broken stiffeners; (2) surface flaws at holes or other stress raisers; (3) arbitrary shaped holes; and (4) arbitrary shaped delaminations. An example illustrating how the software can be used to design least weight/cost structures that satisfy damage tolerance constraints (i.e., residual strength and life) is presented.