Pionic photons and neutrinos from cosmic ray accelerators

► Prospects for detecting gamma rays and neutrinos associated with cosmic rays. ► Gamma rays and neutrinos point back at their sources, unlike charged cosmic rays. ► Review of the formalism that allows estimation of the flux of neutrinos. ► Supernova remnants are suspected to be the sources of the Galactic cosmic rays. ► GRBs and active galaxies may accelerate cosmic rays to the highest energies observed.