This study investigates the utilization of guided waves for inspecting structures that consist of multiple layers. Advances have been made in recent years using guided waves to inspect single layer structures, such as pipes, tubes, and aircraft structures. Multi‐layered structures present many new aspects to guided wave propagation. A theoretical understanding of what modes exist, how do the modes behave, and what factors influence them needs to be acquired for many applications. Experiments must be carried out to evaluate potential for practical applications. Examples of practical applications include coated pipes, composites, diffusion bonded aircraft structures, and microelectronic structures. This work is a fundamental study of ultrasonic guided waves in multi‐layered plates. Experiments were conducted on multi‐layered plates to demonstrate defect detection in layer of interest of a multi‐layered structure by preferentially exciting modes with sufficient energy in that layer. Analysis of the dispersion curves show that some modes are more attractive candidates than others based on their displacements and energy distribution across the structure. Experimental results show that sweeping frequency and phase velocity can be performed to find suitable modes for inspecting a layer of interest for a given multi‐layered structure. © 2004 American Institute of Physics