These proceedings present the lectures given at the twenty-third specialized course organized by the CERN Accelerator School (CAS), the topic being 'Magnets'. The course was held in Bruges, Belgium, from 16 to 25 June 2009. This is the first time this topic has been selected for a specialized course. Taking into account the number of related applications currently in use in accelerators around the world, but, even more important, the worrying decrease in the corresponding expertise in the different laboratories, it was recognized that such a topic should definitively be incorporated into the CAS series of specialized courses. The specific aim of the course was to introduce the participants to the basics of resistive magnet design and its underlying theoretical concepts. The first part of the school dealt with basic introductory courses such as Maxwell's equations for magnets, beam optics, physics and measurement of magnetic materials, the different types of resistive magnets and their respective performance, ... : 14 lectures, 494 pages, published as CERN Yellow Report http://cdsweb.cern.ch/record/1158462 ...