This article provides a foundational framework for understanding student leadership training. The authors categorize the article into three key areas: the "who" defines student leadership trainers as educators who intentionally foster leadership development, with a strong focus on identity exploration, leadership knowledge, and experiential learning. The "what" explores the nature of leadership training, distinguishing it from leadership education, development, and engagement, emphasizing skill cultivation in immersive settings. The "why" highlights the importance of leadership training, stressing practical skill development, reflection, and real-world application. The article positions leadership training as essential for empowering students to engage with leadership challenges through hands-on, reflective experiences that enhance their competencies. Ultimately, this article serves as an introduction to the special issue on leadership development in training contexts.