A simultaneous understanding of the results of the LSND experiment indicating&ngr;&mgr;−&ngr;eoscillation together with other evidences for neutrino oscillations from solar and atmospheric neutrino data seems to require the existence of at least one sterile neutrino. One can also give other plausible astrophysical arguments that seem to require light sterile neutrinos. If such sterile neutrinos exist, a major theoretical challenge is to understand why they are so light. A scenario for the light sterile neutrino is presented where one assumes a parity doubling of the standard model with identical matter and gauge content. The neutrinos of the parity doubled (mirror) sector are light for the same reason that the known neutrinos are light and since they do not couple to the known W and Z bosons, they can be identified with the sterile neutrinos. Some of the implications and possible tests of this hypothesis are mentioned. ©1999 American Institute of Physics.