Membership in research associations and networks (selection)
Since 2010
Chairman of the Hanseatic History Society
Since 1997
Chairman of the „Förderverein Museum Burgkloster zu Lübeck e.V.“, which was renamed in 2017 „Förderverein Europäisches Hansemuseum und Burgkloster zu Lübeck e. V.“
Since 1994
Member of the board of the Hanseatic History Society
Since 1990
Member of the board of the "Verein für Lübeckische Geschichte und Altertumskunde"