Current

	Founding co-editor-in-chief (with John Riedl) of the ACM Transactions on Interactive Intelligent Systems (TiiS).
	Associate chair for CHI 2013, the Conference on Human Factors in Computing Systems (27 April – 2 May 2013, Paris, France)
	Chair of the International Scientific Advisory Board of the research program Continuous Access To Cultural Heritage (CATCH), funded by the Netherlands Organisation for Scientific Research (NWO)

Earlier (Selection)

	Program cochair (with John Riedl) of IUI 2005, the International Conference on Intelligent User Interfaces (9-12 January 2005, San Diego)
	Member of the editorial board of User Modeling and User-Adapted Interaction: The Journal of Personalization Research (1993 - 2001)
	Member of the editorial board of Acta Psychologica (1988–1995)
	Co-chair (with Cécile Paris) of the program committee of UM97, the Sixth International Conference on User Modeling (Sardinia, June 1997) Complete on-line proceedings, including rich index
	Executive officer, from March 1996 through September 1999, of the German Cognitive Science Society (Gesellschaft für Kognitionswissenschaft e.V.)