The first edition (Spanish only version) of this book was a great success, first printed in 2001, and its second edition in 2004 was a confirmation not only of that earlier success, but also of a renewed interest in library architecture. This first English version could also be seen as a third edition, given that the first appendix, covering guidelines, is totally new; the numerical data in the second appendix has been revised, and the section dedicated to projects now includes the Jaume Fuster library by Josep Llinàs and Joan Vera. Also information dealing with legal and regulatory framework now has an international focus. This is a practical book which accurately and thoroughly summarizes all the aspects of interest which crop up during project completion, but in such a way it can be easily understood. Moreover, the 21 works which have been selected, mostly from Catalonia and the Iberian Peninsula, are presented as examples of a variety of solutions and high architectural quality.