|Detecting photons and neutrinos is crucial for studying the nature of ultrahigh-energy cosmic-ray (UHECR) sources. Motivated by the recent Auger data, we consider two possibilities for UHECR sources. One is that the sources are transient proton accelerators, which may be suggested by the Auger results on anisotropy. In this case, we show that ultrahigh-energy photons are a good probe of the UHECR sources, as well as neutrinos. Another is that the sources are nuclei accelerators, which may be suggested by the Auger results on mass composition. In this case, we show that de-excitation photons are useful as a probe of nuclei acceleration. In addition, we argue that the background flux of neutrinos produced by photomeson production would be small from the requirement that UHE nuclei can leave the sources without significant photodisintegration.