Acoustic microscopy offers the possibility of examining the elastic properties of a specimen with spatial resolution comparable with that obtained using a conventional light microscope. This book provides an account of the techniques for both of those who are new to it and wish to find out what they can reasonably expect from it, and for those who are already using it and wish to understand their results better and go on to more advanced work. Examples of its applications that are given include studies of glass-ceramic matrix composites, geological specimens of granodiorite rock, and the matrix secreted from human bone-derived cells- examples which serve to illustrate applications in which the ability to image mechanical properties directly is of tremendous interest. The factors governing the design and operation of an acoustic microscope are described, and an account of theory is given with the specific aim of guiding contrast interpretations and explaining the various methods of quantitative measurement available. Details are provided of the wide range of applications of acoustic microscopy that have been developed in biology and materials.