A substantial fraction of the radiation from an active galactic nucleus (AGN) is apparently nonthermal in origin, and is probably produced by ultrarelativistic electrons. How much energy goes into relativistic protons is uncertain, but it is likely to be comparable to the electron energy or larger. Indeed, several authors (Sikora et al. 1987; Kazanas and Ellison 1986; Zdziarski 1986) have shown that proton-photon and proton-proton collisions can be efficient sources of relativistic pairs in the central engine of an AGN. Thus it is not necessary for electrons to be accelerated directly in AGNs, provided that protons are accelerated with high enough efficiency.