This book deals with the application of grazing angle x-ray and neutron scattering to the study of surface-induced critical phenomena. With the advent of even more advanced synchrotron radiation sources and new sophisticated instrumentation this novel technique is expected to experience a boom. The comprehensive and detailed presentation of theoretical and experimental aspects of the scattering of evanascent x-ray and neutron waves inside a solid makes this book particularly useful for tutorial courses. Particular emphasis is put on the use of this technique to extract microscopic information (correlation functions) from the real structure of a surface, from buried and magnetic interfaces and from surface roughness.