Extending the standard model with heavy right-handed neutrinos below the electroweak scale can simultaneously explain the baryon asymmetry of the universe via leptogenesis and the observed neutrino masses via the seesaw mechanism. The requirement to explain both of these phenomena imposes constraints on the mass spectrum of the heavy neutrinos, their flavor mixing patterns and their CP properties. I will review the low-scale leptogenesis mechanism, and discuss how to test whether right-handed neutrinos, if discovered in the future, can indeed be the origin of both the light neutrino masses and the baryon asymmetry of the universe.