There is a large and increasing variety of polymers currently in use both for domestic and industrial applications. The properties of polymers are deter­ mined not only by their chemical type, but also by their molecular mass and molecular mass distributions. However, while the chemical type of polymers can be determined relatively easily, the average molecular masses and molecular mass distributions are more difficult to measure. The molecular mass averages of a polymer are measured by specialized and complex techniques such as light scattering (for weight average) and osmometry (for number average). Thus, complete characterization of the molecular mass distribution of a polymer by such means requires separating the sample into many fractions which can then be examined individually. Since size exclusion chromatography was introduced as a rapid and straightforward technique for the characterization of polymer molecular mass distributions, there have been tremendous increases in development and applications, and it was felt appropriate to bring together into a single volume the information required by scientists from many disciplines who wish to use the technique. This book should be useful to existing users, those who are new to the technique, and those who may be familiar with the basic technique and now wish to extend their capabilities to more complex applications (or to consider the potential of a number of related techniques). The book will also be of general interest to the experienced liquid chromatographer.