With the development in recent years of NMR spectrometers capable of recording with a minimum of effort data that are both accurate and reproducible, a need has arisen for spectra catalogs and data books to aid the researcher. The ability to correlate a spectrum to a precalibrated chart accurately (to within 0. 02 ppm) has made chemical shift, along with the character of the spectral lines produced, an increasingly important tool in configurational analysis-a tool which this book is designed to complement. It is known that the chemical shift of a proton can be influenced by atoms as much as five or six carbons away, a fact of great importance to compound identification. The entries in this book, arranged according to proton environment, enable the researcher with a hypo­ thetical structure already proposed for his unknown quickly to locate examples of compounds having similar structures. An index of molecular formulas and a shift index, which should prove useful in hypothesizing alternate structures for the unknown and in checking out the hypotheses, have also been provided. The data collected represent some 4800 shifts from the spectra of about 1200 compounds that appear in the catalogs of Varian Associates, Sadtler Research Laboratories, and the American Petroleum Institute, whose cooperation is gratefully acknowledged. The alphanumerical code that is the basis of our presentation, and the explanation of its use, are borrowed intact from the NMR Spectra Catalog of Varian Associates, for whose permission to use this material we are especially grateful.