Pecos National Historical Park Land Exchange Act of 2000

Title I: Addition of Cat Island to Gulf Islands National Seashore - Amends Federal law governing the Gulf Islands National Seashore to encompass within it a specified parcel of land on Cat Island, Mississippi. Grants the Secretary of the Interior acquisition authority with respect to specified lands, including submerged lands and an easement.

Declares that the State of Mississippi shall not be required to convey to the Secretary any right, title, or interest in or to the buffer zone as a condition for the establishment of such buffer zone.

Retains State of Mississippi regulatory authority over maritime activities, including nonseashore fishing activities in areas outside the designated seashore boundary (including the buffer zone).

Authorizes the Secretary to enter into agreements with: (1) the State of Mississippi for law enforcement and resource management purposes; and (2) the owners of the "Boddie Family Tract."

Authorizes appropriations for land acquisition.

Title II: Pecos National Historical Park Land Exchange - Pecos National Historical Park Land Exchange Act of 2000 - Provides for a land exchange between private landowners, the Secretary of the Interior, and the Secretary of Agriculture under which certain lands will be added to the Pecos National Historical Park in New Mexico in exchange for certain lands (and a related easement) within the Santa Fe National Forest in New Mexico. Requires the equalization of values of lands exchanged.