Endangered Species Listing and Delisting Process Reform Act of 2001 - Amends the Endangered Species Act of 1973 to direct the Secretary of the Interior, when required under such Act to use the best scientific and commercial data available in the determination of a species for inclusion on the endangered or threatened list, to use data that are empirical or have been field-tested or peer-reviewed. Allows the Secretary to make such a determination only if there is sufficient biological information to support recovery planning for the species.

Adds certain information required in a petition to add a species to the endangered or threatened list. Requires the Secretary to notify and provide a copy of such petition to an agency of each State in which the species is believed to occur and to solicit the assessment of such agency as to whether the petitioned action is warranted.

Directs the Secretary, upon publication of a proposed regulation determining an endangered or threatened listing, to make publicly available all information on which the determination is based, as well as all information relating to the species that does not support such determination (with an exception for disclosures protected under the Freedom of Information Act or the Privacy Act).

Directs the Secretary to establish criteria that must be met for scientific and commercial data to be used in a determination that a species is endangered or threatened.