  The existence of dark matter is currently one of the strongest motivations
for physics beyond the standard model. Its implications for future colliders
are discussed. In the case of neutralino dark matter, cosmological bounds do
not provide useful upper limits on superpartner masses. However, in simple
models, cosmological considerations do imply that for supersymmetry to be
observable at a 500 GeV linear collider, some signature of supersymmetry must
appear before the LHC.
