  We explain why it is necessary to use boundary conditions in the proof of
supersymmetry of a supergravity action on a manifold with boundary. Working in
both boundary (``downstairs'') and orbifold (``upstairs'') pictures, we present
a bulk-plus-boundary/brane action for the five-dimensional (on-shell)
supergravity which is supersymmetric with the use of fewer boundary conditions
than were previously employed. The required Gibbons-Hawking-like Y-term and
many other aspects of the boundary/orbifold picture correspondence are
discussed.
