Maarten Koornneef was born in 1950 in De Lier in the west of The Netherlands as the son of a vegetable grower. He studied plant breeding at Wageningen University and, after obtaining his MSc, he worked for 2 years as breeder of horticultural crops in a plant-breeding company. In 1976, he moved back to Wageningen to work as assistant professor in the Department of Genetics, where he started his PhD on Arabidopsis genetics with Jaap van der Veen, at a time when only a few laboratories in the world worked on this botanical Drosophila. Through efficient use of the resources and the vast experience present in the group, rapid progress could be made on the genetic and physiological characterization of various groups of mutants. This was done often in collaboration with other departments of Wageningen University. After obtaining his PhD in 1982 on ‘The genetics of some plant hormones and photoreceptors in Arabidopsis thaliana’, Maarten anticipated that tissue-culture technology would become important in plant genetics, but Arabidopsis was considered unsuitable to be used for that technology. Furthermore, the apparent lack of interest in his work partly contributed to a change of topics. This led to a sabbatical at the Friedrich Miescher Institute in Basel, Switzerland to learn about tissue culture in the group of Pat King. Over the past 15 years, the emphasis of his research has been on the study of various aspects of natural variation, mainly in Arabidopsis, but he has also worked on tomato and barley. Maarten's research, especially on the development of the genetic basis of many traits in Arabidopsis, has been recognized by his election as member of the national academies of The Netherlands, USA, Germany, and The European Academy of Science. In 2010, he was elected as member of European Academy of Engineering.