This paper examines federal auctions for leases on the Outer Continental Shelf (OCS) in the light of the predictions of the first-price, sealed bid, common values model of auctions. We find that the data strongly support the model for auctions in which one bidder is better informed than the other bidders. The evidence for auctions in which bidders have noisy but qualitatively similar information is less conclusive, but is consistent with a model in which each bidder does not know either the actual or potential number of bidders on a lease.