Neutrinoless double beta decay is the best-known tool to probe not only for Majorana neutrino masses but for lepton number violating physics in general. Together with the strong experimental effort to observe this decay, the absolute mass of neutrinos is also probed via cosmological observations, and I will discuss what information can be gained from combining future searches. On the other hand, the LHC has a strong potential to probe lepton number violating physics at the TeV scale. I will highlight this potential for the case of Left-Right symmetrical models with right-handed neutrinos accessible at the LHC, and I will generally discuss possibilities to discriminate and test different mechanisms in complementary experiments.