Expatriate Terrorists Act - Amends the Immigration and Nationality Act to include among the grounds for loss of U.S. nationality by a native-born or naturalized citizen:

• taking an oath or making a declaration of allegiance to a foreign terrorist organization after attaining the age of 18; or
• becoming a member of or providing training or material assistance to any foreign terrorist organization that such person knows or has reason to know will engage in hostilities against the United States, or will commit acts of terror against the United States or U.S. nationals.

Adds to the conditions referring to service in the armed forces of a foreign state or a foreign terrorist organization that such armed forces are engaged in hostilities against the United States (as under current law) or intentionally targeting U.S. nationals for acts of terror.

Declares that there shall be a loss of nationality by accepting, serving in, or performing the duties of an office, post, or employment under the government of a foreign state or a political subdivision after attaining the age of 18 if the person (under current law, a man) knowingly has or acquires the nationality of such foreign state (while current law does not require a knowing state of mind).

Declares also that there shall be a loss of nationality by accepting, serving in, or performing the duties of an office, post, or employment under the government of a foreign state or a political subdivision after attaining the age of 18 which requires an oath, affirmation, or declaration of allegiance to the foreign state or political subdivision.