Active galactic nuclei and starburst galaxies have been pointed out as the most promising sources for producing ultra-high-energy cosmic rays. In this talk, I will discuss the feasibility of accelerating particles up to the highest energies in starburst galaxies and AGN jets. In particular, I will present results for the acceleration of particles in the large-scale shocks of the superwinds of starburst galaxies and show a scenario in which cosmic rays could be generated in multiple shocks created by the interaction of relativistic AGN jets with stars.