Change all but defines the late nineteenth and early twentieth centuries in American history. In the midst of these tumultuous times, America experienced a revolution of reform meant to develop and enhance all areas of life from politics to society, which led historians to call this time period the Progressive Era. However, the progress of the nation was not always the winning ideology. At times, the backlash against progressive ideas restrained innovators and caused them to disappear into the mires of history. One reformer who experienced this backlash was Fred Morrow Fling. Although he was an internationally-known historian, he remained a rather invisible history education reformer because his ideas were overshadowed by the enormous human events of his lifetime, including the work of other reformers and his unexpected death in 1934. As a trained scientific historian, Fling was a pioneer of historical method and the application of what became known as “source method” in the classroom and he espoused a radical approach to critical education that sought to embed a scientific approach into the teaching of history that has clear parallels with best teaching practices today. Thus, using traditional historical research methods and archival records from both Bowdoin College and the University of Nebraska, the author presents in this dissertation a biographical portrait of Fling’s life. Through the analysis of these historical documents and the evidence of his life recorded in publications and the public press, this portrait will serve to uncover both how Fred Morrow Fling’s conception of history education influenced his practice as a history professor and researcher and how Fred Morrow Fling’s philosophy of education formed and developed over his lifetime. Specifically, this author will consider: how can the philosophy of history education created by Fred Morrow Fling inform our current history education practices today? By investigating Fling’s life, researchers will finally be able to acknowledge Fling’s myriad contributions to history education, which are vital to composing a fuller picture of the history of social studies education.