  Both the first evidence and the first discoveries of neutrino flavor
transformation have come from experiments which use neutrino beams provided by
Nature. These discoveries were remarkable not only because they were
unexpected--they were discoveries in the purest sense--but that they were made
initially by experiments whose primary goals were aimed at other physics.
Future solar and atmospheric neutrino experiments will also be sensitive to a
broad range of physics and thus to new and unexpected phenomena. We discuss
here the physics which can be done by new solar and atmospheric neutrino
experiments and what we believe to be the highest priorities for the next
generation of detectors.
