Open problems in particle astrophysics

This contribution outlines some of the highlights of the Roma International Conference on Astroparticle Physics (RICAP) 2011. The efforts to understand the 'high energy universe' constitute a vibrant field that, thanks to the observations of different detectors for gamma-rays, cosmic rays and neutrinos, continues to generate surprising and exciting results. The progress in the field is rapid but many fundamental problems remain open. The search for an understanding of the nature of the Dark Matter remains one of the fundamental open problems in science, and is intimately connected to the study of the high energy universe.