Already in the 1970s Knud Illeris was well known in Scandinavia for his developing work on project studies in theory and practice. In this work, learning theory was applied, mainly by a combination of Jean Piaget’s approach to learning and the so-called ‘critical theory’ of the German-American Frankfurt School that basically connected Freudian psychology with Marxist sociology. In the 1990s, Illeris returned to his learning theoretical roots, now involving many other theoretical approaches in the general understanding of learning, which was fi rst presented in The Three Dimensions of Learning and later fully worked out in How We Learn: Learning and Nonlearning in School and Beyond. The following chapter presents the main ideas of this understanding and is an elaborated version of the presentation Illeris made at a conference in Copenhagen in 2006 when the Danish version of How We Learn was launched. The article has never before been published in English.