This dissertation examines the Christology of Jon Sobrino by using martyrdom as a lens. Sobrino deliberately expands the concept of martyrdom beyond the traditional definition. This dissertation shows how Sobrino expands the concept of martyrdom. Martyrdom arises within Sobrino's Christology and marks it in a unique way, especially as Sobrino has refined his theological voice over the last decade. An expanded definition of martyrdom changes his Christology. This is evidenced by the differences between his work Christology at the Crossroads, the later works Jesus the Liberator and Christ the Liberator, and his writings on martyrdom since the early 1990's. There is a dialectical relationship within Sobrino's Christology. The idea of the Jesuanic martyr influences Sobrino's Christology, and his Christology marks his idea of what constitutes a martyr, pushing both the concept of martyrdom and his own Christological questions in new and interesting directions.  The initial chapter outlines three main areas: 1) the traditional notion of martyrdom 2) a 20th century understanding of martyrdom and 3) an initial placement of Sobrino's understanding of martyrdom in the current debate. The second chapter gives a brief history of martyrdom in Latin America in the 20th century, eventually focusing on the history of El Salvador during the 1980's in relation to Sobrino's life. This illuminates the context from which his Christology emerges. Four examples of martyrs are developed: Rutilio Grande, S.J., Archbishop Romero, the U.S. churchwomen, and the UCA Jesuit community. The third chapter outlines the key elements present in Sobrino's Christology before the death of his companions in 1989. Basic elements from Christology at the Crossroads serve as a bridge to analyze his later work. The final chapter examines Sobrino's Christology after the death of his companions in 1989. Key elements identified in his earlier work show substantial development in Jesus the Liberator and then Christ the Liberator. This fourth chapter shows how the reality of martyrdom serves as an optimal lens for viewing Sobrino's Christology.