The search for proton decay and other rare phenomena

The first results from the Irvine-Michigan-Brookhaven proton decay experiment are summarized. The partial lifetime for the decay p - e(+)pi(0) is found to be longer than the value calculated from the minimal SU(5) theory, with the best presently available estimates for the parameters needed. The detector is sensitive to some other potential decay modes as well as to some rare phenomena that have been discussed in recent years. The characteristics of the observed penetrating cosmic ray muons and atmospheric neutrino interactions are compatible with expectations.