Book excerpt: Examines the evolution of U.S.-European Union (EU) counter-terrorism cooperation. Contents: (1) Background on EU Efforts Against Terrorism; (2) U.S.-EU Counter-terrorism Cooperation: Progress to Date; New Law Enforce. and Intell. Cooperation Agree.; Stemming Terrorist Financing; Border Control and Transport Security: Container Security; Passenger Name Record Data; Aviation Security; (3) Ongoing Challenges: Data Privacy: Tracking Terrorist Financing; Sharing Airline Passenger Data; U.S.-EU Framework Agree. on Data Protection; Balancing Transatlantic Travel, Commerce, and Security: Visa Waiver Program; Cargo Screening; Detainee Issues and Civil Liberties; Differences in the U.S. and EU Terrorist Lists.