A Robust Design Optimization (RBO) computational approach has been developed to maximize the Durability and Damage Tolerance (D&DT) and Reliability of composite stiffened panel structure with 2 bay cracks. Robust design optimization is integrated in GENOA D&DT by means of coupling Multi-Scale Progressive Failure Analysis (MS-PFA), Reliability, Optistruct FE Optimizer, and Hypermesh software. The integrated software capability is utilized to minimize weight, maximize peak load and the residual strength, and enforce the directionality of cracks growth turning for safe design. The random variable parameters considered are: a) skin/stiffener load ratio, stiffeners height/width, and ply angle orientation in the stiffener and skin. The capability provides engineers with the predictive computational technology to characterize and qualify advanced composites materials and structures while considering manufacturing anomalies. First, the D&DT analysis prediction was performed using stiffened panels with imbedded 2-bay skin cracks under compression and tension loading. Results are compared with test: a) Load-displacement curve, b) Crack Growth direction; and c) Strain Gauge and photoelastic measurements. Second, we performed risk mitigation utilizing the Reliability Based Design Optimization to improve the failure evolution (translaminar, and interlaminar) with the main objective to increase the load displacement and turn crack(s) for confinment and safety.