This chapter explores how psychological science can inform and transform the fire service. Despite its relevance, psychology remains underused due to cultural stigma, hypermasculinity, and decentralized systems. The chapter examines how trauma, moral injury, coping strategies, and organizational stress shape firefighter mental health. It also reviews evidence-based practices, including peer support, emotional intelligence, and recovery strategies, and advocates for the systemic integration of psychology to support resilience, performance, and well-being throughout all phases of a firefighter’s career.