The project method, a hallmark of the American progressive education movement, ranks among the most influential instructional approaches worldwide. Yet its origins and evolution—shaping classrooms and universities in Europe and the United States for over 450 years—have been largely overlooked. This study ventures to provide the first comprehensive account of that development, tracing the method from its Italian and French roots to its transatlantic transfer, examining its elaboration during the Progressive Era, and exploring, among other highlights, John Dewey’s critique of William H. Kilpatrick’s provocative definition of the project method. From a conceptual and historical perspective, it illuminates the trajectory of the progressive education movement—charting its little-known beginnings and analyzing its defining discourses.