Ammeter pegged...

When I first fire it up, the ammeter will peg out.
Which way? Charge or Discharge?
Pegged indicates 40 amps or more are flowing out of, or into the battery. Which is it?
Have I got a bad altenator? Bad regulator? Help an electrical illiterate brother out before I fry something.
As Del noted, having a voltage reading will help ID the problem, especially if its pegging to charge.