a1 Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN
a2 Institute of Astronomy, The Observatories, University of Cambridge, Madingley Road, Cambridge CB3
a3 Department of Astronomy and McDonald Observatory, University of Texas, 1 University Station C1402, Austin, TX 78712-0259
Knowledge of the nature and mass of the progenitor stars of core-collapse supernovae are critical elements to test theoretical models of stellar evolution and stellar explosions. Here we describe the current limits and restrictions that can be placed on the progenitor stars of type II SNe and those of Ib/c. There are detections of some type II-P SN progenitors but the exploding stars that produce type Ib/c have eluded discovery. We discuss implications of these quantitative limits and the conclusions that we can now draw.