If you acted as safety pilot, and were legally qualified to do so (i.e.
current medical and rated in category & class), then you may log SIC time.

In order to log PIC time, as others are suggesting, you would need to be
qualified to act as PIC in the a/c (i.e. all endorsements, currency
requirements, etc.) and, according to FAA legal counsel, also have had an
agreement with the pilot flying, prior to the flight, that you would be
legally responsible for the flight of the aircraft.

Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Well to clarify, I do have all the requirements met.
I am a private pilot, checked out in the C172SP that we flew and I am
current.
Our agreement as safety pilot was that I would be the eyes outside the
aircraft to
see and avoid other aircraft (such as the B727 that took off from SFB and
crossed
ahead of our path.).
It is the see and avoid that I believe makes me responsible for the over all
flight path.
Since this was under-the-hood flying and not actual IMC it was also my
responsibility
to decide if the aircraft was under the proper control and to assume control
should I
feel it to be necessary.

David (KORL)