
I will review the motivations for “grand unification” of forces and of matter particles and the experimental hints in its support. These theoriesnaturally predict small neutrino masses, leading to neutrino oscillations. Predictions of minimal theories for neutrino oscillation parameters will be shown to be in excellent agreement with recent data. The hallmark of these theories is the prediction that protons should ultimately decay, with a lifetime potentially within reach of ongoing experiments. A cosmological connection between proton decay and the origin of matter in the universe will be discussed.<?xml:namespace prefix = o />