Supermassive black holes as sources for LISA

I briefly discuss some issues relevant for the formation of supermassive black holes and give estimates of the event rates for the emission of gravitational waves by coalescing supermassive black hole binaries. I thereby use models which take into account recent improvements in our knowledge of galaxy and star formation in the high-redshift universe. Estimated event rates range from a few to a hundred per year. Typical events will occur at redshift three or larger in galaxies lying at the (very) faint end of the luminosity function at these redshifts.