The investigation and understanding of the immune response to dengue, including its protective and pathogenic functions, present unique challenges, particularly due to the circulation of four distinct serotypes. While infection with one serotype induces long-term protection, including some level of temporary cross-protection against other serotypes, epidemiological evidence suggests an increased risk of severe disease following subsequent heterologous infections. Although the antibody-mediated response has been more extensively studied in this context, it is also evident that T cell immunity contributes to infection resolution and long-term memory, but in some circumstances, it can influence immunopathology. In this chapter, we will present findings regarding T cell–specific DENV epitopes and activated T cell repertoire and discuss the role of distinct T cell subtypes and their functional association with protection, memory response, as well as how altered T cell responses can contribute to disease severity. A deeper understanding of these mechanisms is essential for elucidating disease pathogenesis and identifying key protection and disease markers, which are critical for the development and efficacy assessment of dengue vaccine. In addition, T cell–mediated immunity should be considered in the design and implementation of immunization programs.