To render all enrolled members of the Tohono O'odham Nation citizens of the United States as of the date of their enrollment and to recognize the valid membership credential of the Tohono O'odham Nation as the legal equivalent of a certificate of citizenship or a State-issued birth certificate for all Federal purposes.

Tohono O'odham Citizenship Act of 2003 - Amends the Immigration and Nationality Act to recognize persons listed on the official membership roll of the Tohono O'odham Nation, a federally recognized American Indian nation located in Arizona, as U.S. citizens as of the date such listing occurs. Provides that the valid membership credential issued to such listed persons shall be considered, for all purposes subject to Federal law, equivalent to: (1) a certificate of citizenship; and (2) a State-issued birth certificate.