Failure of a structural element occurs when it cannot perform its intended function. Material fracture is the obvious type of failure but not the only one. Excessive deflection is also a type of failure if the performance or the aesthetic value of the structure is compromised. Even if the part does not collapse, partially damaged materials may be considered failed, for example if cracking affects the aesthetic value of the structural element. Deflections are easier to predict than damage and fracture. Predictions of deflections are addressed in Chapters to and in examples throughout this book. The objective of this chapter is to describe strength design; that is, to develop tools to predict damage and fracture of laminated composites and to use those tools to select materials, configurations, and dimensions that allow the structure to safely perform its function.