Previous organizational matters
I have organized the semi-annual Diamant symposium from 2010--2019.
I have organized several of the Diamant mini-symposia at the NMC (2011, 2012, 2013, 2014, 2018).
Effective Methods for Diophantine Problems: a conference at the Lorentz Center (June 2018, with Attila Bérczes, Bas Edixhoven and Kálmán Győry)
Heights and moduli spaces: a conference at the Lorentz Center (June 2013, with Gerard Freixas i Montplet and Gerard van der Geer)
Geometry and arithmetic: a conference on the occasion of Gerard van der Geer's 60th birthday (September 2010, with Carel Faber and Gavril Farkas). Proceedings volume has appeared in the EMS Series of Congress Reports
Intercity Seminar Algebraic Geometry (Fall 2010, with Jochen Heinloth)