This is the fifth volume of a series which provides acontinuing forum for publication of developments in Mossbauer effect methodology and of spectroscopy and its applications. Mossbauer Effect Methodology, Volume 5, records the proceedings of the Fifth Symposium on Mossbauer Effect Methodology. The sym­ posium was sponsored by the New England Nuclear Corporation and was centered on the themes of spectroscopy, new applications, and methodology. The symposium was held in the Mercury Ballroom of the New York Hilton hotel on February 2, 1969. Dr. P. A. Flinn of Carnegie­ Mellon Institute was chairman of the afternoon and evening sessions. About three hundred participants attended, and this degree of interest leads us to anticipate a sixth symposium early in 1970. Elron Electronic Industries and Reuter-Stokes Electronic Components Company demonstrated lines of equipment for Mossbauer investigators. The evident high quality of the commercial instrumenta­ tion available is a tribute to the growth of Mossbauer technology and to the manufacturers.