  Lepton number violation could be manifest in the sneutrino sector of
supersymmetric extensions of the standard model with conserved R-parity. Then
sneutrinos decay partly into the ``wrong sign charged lepton'' final state, if
kinematically accessible. In sneutrino pair production or associated single
sneutrino production, the signal then is a like sign dilepton final state.
Under favourable circumstances, such a signal could be visible at the LHC or a
next generation linear collider for a relative sneutrino mass-splitting of
order ${\cal O}(0.001)$ and sneutrino width of order ${\cal O}$(1 GeV). On the
other hand, the like sign dilepton event rate at the TEVATRON is probably too
small to be observable.
