Knud Illeris’ name is predominantly associated with the development of comprehensive understanding and explanation of how human learning and non-learning takes place.

As a young man Illeris had a quite promising career as a travel agent. Gradually though, he developed a need for more mental simulation so decided to start an A-level course. However, what he experienced was a great disappointment. The lessons were boring, the teaching authoritarian and most of the content he found antiquated. He soon came to see the course as a means to sort out students with low cultural capital and favor those with a more suitable background. This gave rise to the idea that a proper understanding of the process of learning could lead to better and more effective way of teaching and schooling.

He soon involved himself in a group which in a couple of years succeeded in establishing an alternative 'free' upper secondary school, an innovation which is just now celebrating its 40 year anniversary. At the same time he started studying psychology at the Copenhagen University with a focus on learning processes. However this was another great disappointment, in his eyes the dominating behaviourist understanding did not give any relevant answers. But some older students turned his attention to the ideas of significant learning and student-cantered teaching. Ideas that came from amongst others the American humanistic psychologist Carl Rogers, who had taken up the understanding of learning and development launched by the Swiss biologist Jean Piaget.

Gradually by combining these approaches with the Freudomarxist framework of the German Frankfurt School (especially the sociologist Osker Negt), Illeris after four years' study could see the outlines of a broader understanding of learning. That following year he could present a dissertation which after the regulations at that time was accepted as both an MA and what corresponds nowadays to a Ph.D.

At the same time, in 1972, he was attached as an associate professor to the new experimental Roskilde University where all studies and research was to be project based. He devoted most of his time to work out the theory and practice of project education – a work which was highly estimated and became widely known in the Scandinavian countries from primary school to university level and not least in adult education.

For many years Illeris worked intensively with educational practice, mainly in youth and adult vocational training, and it was not until the 1990s that Illeris on these foundations again turned his academic attention towards fundamental learning theory. New works of mainly American and German scholars had now made it possible to further elaborate his ideas and in 1998 a sabbatical made it possible to link up old and new ideas in the comprehensive theory of learning which was published in Danish in 1999 and in English in 2002.

This book together with a lot of articles on the topic soon gave Illeris a broad international breakthrough, and today he has been published in 13 languages, including Chinese, and he has lectured in 26 countries in five continents. He has also been appointed an Honorary Adjunct Professor at Columbia University, New York, a member of the International Adult Education Hall of Fame, and received the Dutch Chris Argyris Award of Organizational Learning as the first to do so after Chris Argyris himself. Illeris is also a member of the scientific board of the German Adult Education Institute (DIE) and the editorial board of the American Human Resource Development Review. Since 2009 Illeris has together with a colleague mainly worked in their private consultancy: Simonsen & Illeris Educational Consultants. www.simil.dk

Altogether, Illeris has been the author, co-author or editor of close to a hundred books and research reports and more than 300 academic articles and chapters in Danish, and in English 14 books and reports and 60 articles, chapters and papers. Since 2007 his English works have mainly been published by Routledge.