Chapter 11 First Price Independent Private Values Auctions The first price sealed bid auction is the market institution in which the high bidder acquires ownership of the auctioned item and pays a price equal to the amount of the highest bid. This market institution is distinguished from the second price sealed bid auction in which the high bidder obtains the auctioned item and pays an amount equal to the second highest bid. Bids in sealed bid auctions are often literally sealed in envelopes but need not be; the essential distinction is from a real time auction in which the time at which bids are submitted during the auction is an essential feature of the market institution. This chapter presents experimental tests using independent private values of the consistency of bidding behavior in the first price auction with three nested Nash equilibrium bidding models. The reported tests have various implications for the three nested models. Depending on which test is used data for only 010 of the subjects are consistent with the risk neutral model. This conclusion is the same regardless of whether one conducts the tests with market prices individual subjects bids and values or subjects expected foregone earnings. Tests with individual subjects bids and values indicate that data for about 48 of the subjects are consistent with the constant relative risk averse model and data for almost all subjects are consistent with the log concave model.