The medical education community has witnessed lately several trends and innovations in medical education curricula; however, the application of the controversial Problem-Based Learning (PBL) strategy in medical schools was the most widely known major curricular intervention in the last century. In recent years; PBL effectiveness, its research studies, and research in medical education field in general, has been a subject of considerable interest and debate. Although the research is still inconclusive, there is good evidence that PBL approach delivers on some very important issues. This book highlights how the integrity and quality of the research studies in medical education, especially those that evaluated the PBL approach, have evoked many controversial issues.