The COST action “Black Holes in a Violent Universe” (MP-0905) organizes a Summer School on “Black Holes at all scales”, in Ioannina, Greece, betweenSeptember 16 and 18, 2013. The Summer School “Black Holes at all scales” aims at postgraduate students and young postdoctoral fellows. The program includes reviews on various aspects of Black Hole-related science, such as: demographics and formation theories of galactic black hole binaries in our and nearby galaxies, our “own” supermassive black hole on the Galactic center, formation and cosmic evolution of supermassive black holes, phenomenology of active galactic nuclei and a review of their “unification” theories, theory of jet formation and energy extraction in black hole systems, as well as the scaling of accretion and jet physics from mini-quasars to quasars.