This book is devoted to the static properties of flexible polymers in solution. It presents the progress made by both theory and experiment in the years up to its original publication in 1990, and remains one of the most advanced books available on this subject. Despite the variety in the chemical composition and physical properties of long polymer chains, when in solution they show a universality in their behaviour. On the experimental side, the use of photon and neutron scattering has led to a better understanding, while the use of computer simulation has also produced interesting results. This work is the result of a collaboration between a theoretician and an experimentalist, who have both worked for many years on polymer solutions.