Metallic structures are increasingly being replaced by composite materialsComposite materials in a wide range of applications, including aerospace, automotive, civil, and mechanical structures, as well as sporting goods. The primary motivation for this transition lies in the superior strength-to-weight and stiffness-to-weight ratios of composites. In the automotive industry, their enhanced shock and impact absorption capabilities offer an additional advantage. All structures experience damage and degradation during service; therefore, inspection for damage and health deterioration is of paramount importance. In composites, damage typically occurs in two forms: (i) physical damage, where visible or structural failuresStructural failures such as cracks, fiber pull-out, or delamination occur, and (ii) material degradation, involving micro-cracking or matrix deterioration that leads to reductions in stiffness and strength. A reduction in strength does not necessarily imply that a structure is unusable; rather, its performance characteristics are altered. Ultrasonic inspection provides an effective means to detect and quantify both categories of defects. This chapter presents an overview of the ultrasonic inspection of laminated compositesLaminated composites, discussing the principles, techniques, instrumentation, and applications of this important nondestructive method.