  The focus of this chapter lies on the possible experimental tests of
leptogenesis scenarios. We consider both leptogenesis generated from
oscillations, as well as leptogenesis from out-of-equilibrium decays. As the
Akhmedov-Rubakov-Smirnov (ARS) mechanism allows for heavy neutrinos in the GeV
range, this opens up a plethora of possible experimental tests, e.g. at
neutrino oscillation experiments, neutrinoless double beta decay, and direct
searches for neutral heavy leptons at future facilities. In contrast, testing
leptogenesis from out-of-equilibrium decays is a quite difficult task. We
comment on the necessary conditions for having successful leptogenesis at the
TeV-scale. We further discuss possible realizations and their model specific
testability in extended seesaw models, models with extended gauge sectors, and
supersymmetric leptogenesis. Not being able to test high-scale leptogenesis
directly, we present a way to falsify such scenarios by focusing on their
washout processes. This is discussed specifically for the left-right symmetric
model and the observation of a heavy $W_R$, as well as model independently when
measuring $\Delta L = 2$ washout processes at the LHC or neutrinoless double
beta decay.
