Luttrell enlisted in the U.S. Navy in March 1999. After graduating from boot camp and Hospital Corpsman A-school, he transferred to Basic Underwater Demolition/SEAL (BUD/S) Class 226. However, due to a fractured femur he suffered from falling off a rope, he graduated with Class 228 on April 21, 2000. After completing BUD/S, Luttrell attended Army jump school and SEAL Qualification Training (SQT). Luttrell earned his Navy Enlisted Classification (NEC) 5326 Combatant Swimmer (SEAL) and Naval Special Warfare Insignia on February 2, 2001 after completing SQT. He was then sent to Fort Bragg, North Carolina, for the Special Operations Combat Medic (SOCM) course. SOCM was an additional six months of advanced training in conventional and unconventional medical skills, ranging from diagnosis and treatment of many conditions to advanced emergency medicine and battlefield life support.