This book provides a systematic assessment of the quality of Project-Based Learning (PBL) and proposes a diagnostic criteria framework for evaluating project design and implementation. It identifies key characteristics that vary as a result of differentiation. The book offers a feasible framework for implementing competency-based teaching on an international scale, drawing from our long-term exploration in China to address shortcomings in Chinese education. Furthermore, it delineates the boundaries and limitations of project-based design, facilitating professional learning in its implementation. Educational practitioners will gain multidimensional perspectives to develop their capacities and critically reflect on PBL's impact on students' learning processes.