This chapter examines the relationship between online Project-Based Learning (PBL) and social capital development, tracing the historical roots of PBL from learning by doing and experiential learning to modern implementations supported by digital platforms. It highlights how PBL, grounded in student-centered, real-world projects, fosters deep learning and critical thinking. As PBL has evolved, the integration of AI technology offers new tools to enhance learning but also introduces ethical challenges that must be carefully managed. The chapter emphasizes that building social capital – through trust, collaboration, and community engagement – is essential for the success of online PBL. It discusses strategies for overcoming the challenges of diverse student backgrounds and real-world complexities, focusing on the importance of ethical AI use and inclusive practices. Ultimately, this chapter underscores the potential of online PBL to not only enhance academic outcomes but also contribute to stronger, more resilient communities through the development of social capital.