Tuberculosis (TB) continues to be a major global health burden, with the Bacillus Calmette-Guérin (BCG) vaccine offering only limited protection. The urgent need for new and more effective TB vaccines underscores the importance of pre-clinical research. This chapter examines the pre-clinical stages of TB vaccine development, focusing on antigen discovery and the challenges inherent to this process. We detail strategies for identifying promising antigens, from traditional empirical methods to advanced approaches like immunopeptidomics. Additionally, we discuss critical obstacles in TB vaccine research, including the complexity of the immune response to Mycobacterium tuberculosis (Mtb), the absence of reliable immunological correlates of protection, and the limitations of replicating human TB in animal models. By addressing these challenges and enhancing our understanding of TB immunity, we aim to accelerate the development of effective vaccines to combat this devastating disease.