Project-Based Learning (PBL) is a powerful pedagogical approach that fosters deep, interdisciplinary learning by engaging students in meaningful, real-world problems. As STEM education continues to gain prominence in K-16 curricula, the integration of PBL becomes increasingly vital for preparing students to think critically, collaborate across disciplines, and apply their knowledge in authentic contexts. This reprint of the Special Issue of Education Sciences invites scholarly contributions that explore the implementation and impact of project-based learning across K-16 educational settings. The articles in this reprint include original research, theoretical analyses, and descriptions of promising practices that explore how PBL supports four key themes: interdisciplinary STEM learning, civic engagement, equity and identity, and pedagogical innovations and frameworks.