Part 1 Background - The Advanced Tactical Fighter Prior to Milestone Zero: Overview; Air-to-Surface Advanced Tactical Fighter; Introduction of Air Superiority as a Potential Advanced Tactical Fighter Mission; Preparation for Milestone Zero; Request for Information. Part 2 Phase 0 - Concept Definition: Overview; Request for Information Results; Shifting Emphasis - Air Superiority Becomes Primary Advanced Tactical Fighter Mission; Advanced Tactical Fighter Concept Development Investigation; Transition to Demonstration and Validation; Shift to Prototyping. Part 3 Phase 1 - Demonstration and Validation: Overview; System Specification Development; Avionics Ground Prototypes and Flying Laboratories; Prototype Air Vehicles Development and Flight-Test; Additional Programme Events During Demonstration and Validation; Transition to Engineering and Manufacturing Development; Demonstration and Validation. Part 4 Related Technology and Subsystem Developments: Introduction; Avionics; Weapons Technology; Structures and Materials; Low Observables; Supporting Engine Technology Programmes; Flight Demonstrator Programmes Related to Advanced Tactical Fighter; Summary. Part 5 Engine Development: Initial Engine Studies; Ground Demonstration Engines; Flight Demonstrator Engines; Engineering and Manufacturing Development; Engine Engineering and Manufacturing Development and Beyond; Observations on Engine Development. Part 6 Navy Participation and the Naval Advanced Tactical Fighter. Part 7 Conclusion: Requirements Evolution; External Pressures; Final Observations.