Publisher Summary This chapter describes structural safety. The safety of composite structures is a challenging subject for many reasons. The successful introduction of composite structures in all applications is a very worthy target, but only when the innovations possess better than or equivalent levels of safety compared to the structures they replace. According to this chapter, many successful applications have been introduced, but there still is much more to achieve for commercial airliners, and safety is an important ingredient. This chapter discusses primary drivers where damage tolerance is the dominating safety concern in the design of composite structure. The extension of the existing and emerging regulations (advisory circulars, ACs) should be discussed to enable the consideration of states of uncertainty, randomness, and knowledge in a rational way in the design process.