If LETAGROP, MINIQUAD, SCOGS and SQUAD mean something to you, then this is for you an important book. For the uninitiated, these are computer programs for the calculation of formation constants of complexes, which, originating with LETAGROP in 1961, are in current use. Potentiometry and spectrometry are the two most popular experimental techniques for "complex-ion" chemists. The book contains description and collection of authors' programs for the analysis of experimental data from these two techniques which have been independently tested on two computers and the results down-loaded to provide the listings which appear at the end of each chapter. Unfortunately, the new program SUPERQUAD is not included. The first of the nine chapters is an overview, but not an elementary introduction, by the Editor, dealing with the various approaches to the problems of data fitting. The question of whether different computer programs achieve the same result on a given set of data is not addressed. This volume is essential reading and reference material for all active workers in this field, being complementary to the now classic text Determination of Stabiliry Constants by Rossotti and Rossotti (1961) but it will also be of use to other workers interested in the general problem of data fitting.