Astrophysical observations of the structure of galaxies and clusters are no longer simply proving the existence of DM, but have sharpened into a discovery tool probing the particle physics of DM. I discuss small scale structure anomalies for CDM and their possible implications for DM physics, such as the existence of forces in the dark sector. New results on cluster scales provide a new important handle for constraining DM's interactions, its mass, and the mass of dark mediator particles.