Ultra-rare particle physics processes allow to search for effects beyond the standard model up to energy scales well above the reach of the highest-energy colliders. They test symmetries and conservation laws, and enable a detailed understanding of particle dynamics in the early universe and the present-day cosmos. This workshop will focus on rare processes beyond the standard model in particle and astroparticle physics. It will bring together experts from flavour physics, model building, cosmology and precision calculations to discuss the potential implications of the study of rare process at the next generation of collider and non-collider experiments. The workshop topic is central to the whole career of our colleague Daniel Wyler, who will celebrate his 60th birthday at the end of December 2009. The workshop will honour his scientific accomplishments, and unite many of his friends and colleagues.