  No abstract appeared in the Proceedings, but I am adding the following
summary at the request of the X^3 people: The idea of neutrino masses is
discussed in the context of grand unified theories., and various scenarios are
presented, including the seesaw mechanism. At the end, preference is stated for
maximal mixing between $\nu_\mu$ and $\nu_\tau$, and small mixing with $\nu_e$.
