The only means to get direct and immediate information about the
engine of core collapse supernovae is from observations of neutrinos
emitted by the forming neutron star, and through gravitational
waves. The latter are emitted when the explosion involves
time-dependent asphericities because of rotation, magnetic fields,
non-radial flow, and anisotropic neutrino emission. In my talk I will
review the current status of the efforts to predict the gravitational
wave signal of core collapse supernovae, particularly addressing the
results of some recent 3D studies.