MPE, Garching, Germany
The Infrared Space Observatory (ISO) has for the first time made possible mid- and far-infrared spectroscopic studies of nearby and moderate redshift, dusty ultra-luminous infrared galaxies (ULIRGs). A review will be given of recent SWS, LWS ISOPHOT-S and ISOCAM (CVF) results on ULIRGs. The following topics will be addressed: What powers ULIRGs? What is the AGN-starburst connection, how do ULIRGs evolve with time?