The implications of Supernova 1987A are examined and compared with theoretical expectations. The relatively low luminosity follows from the progenitor having lower than solar abundances. The explosion energy is (1.0-2.0) x 10 to the 51st ergs for a 15 solar mass star. The neutrino signal is strikingly like that expected from recent models of the core collapse process with advective overturn. 20 references.