Research on Problem-Based Learning in medical education has undergone an evolutionary process from initial proof of concept studies through critiques of the original methods and beyond. Initial studies focused on whether or not the instructional method was effective for medical students and the goals of medical education. Despite much movement back and forth between results demonstrating effectiveness and ineffectiveness, not much forward progress was made in reaching a decisive conclusion. Recently, however, the adoption of different theoretical perspectives, research methods, research targets and technological supports has begun to move the studies along. Current research in the area is focusing not on whether the students learn, but rather what goes on during learning that helps or hinders their learning. As such the group process and its cognitive components has become a more fruitful target of researchers.