This monograph is intended for use by professional scientists and engineers who are either attempting to familiarize themselves with the relatively new signal processing technique known as of matched field processing (MFP) or who would like further detailed information about some aspect of MFP. That is, it is intended to be both an introductory/tutorial text and a reference source. All the examples are drawn from underwater acoustics applications where the technique has recently enjoyed widespread use. The reader is also assumed to have some familiarity with wave propagation modeling within a context of underwater acoustics This book provides 1.a basic guide to the history and development of MFP including derivations of the most popular processors in use, 2. discusses situations under which MFP has difficulties (either computationally or in practice), 3. gives extensive examples showing how various processors behave under typical conditions, 4. increases reader's awareness of the wide range of applications currently being explored, and 5. exposes readers to important associated publications available in the literature with accompanying remarks suggesting their key conclusions or contributions.