Contains the proceedings of the activity 'Dynamical Numbers: Interplay between Dynamical Systems and Number Theory' held at the Max Planck Institute for Mathematics (MPIM) in Bonn, from 1 May to 31 July, 2009, and the conference of the same title, also held at the Max Planck Institute, from 20 to 24 July, 2009--Preface, p. vii.