Medievalist Paul Stephenson, lead professor at the School of History and Heritage, University of Lincoln, and a Fellow of the Royal Historical Society, expressed high regard for Fine's work and compared him with the likes of Paul M. Barford, Simon Franklin, Jonathan Shepard. His academic interests range from theology and the history of Christianity to Byzantium and the medieval and modern Balkans. His publications have become standard in the field, notably his surveys of the Medieval Balkans. He has also revolutionized the way scholars understand the Bosnian Church, showing that it was not heretical. In 2006, Fine published a study of notions of ethnicity in Croatia from the medieval period to the nineteenth century titled When Ethnicity Did Not Matter in the Balkans. In 2008, Emily Greble Balić, gave positive review stating that "ne of the book's great strengths is Fine's analysis of premodern "ethnic" identity". In 2009, John K. Cox of North Dakota State University reviewed it largely positively, noting some points of criticism. James P. Krokar review from 2009 was also positive, stating that the book is "extremely important" addition to "South Slavic history, and to the debate on the modernity of the nation." The same year, of the University of Zagreb gave a negative review, stating that "Fine's book cannot in any way merit a positive review. It clearly shows how ideological prejudices affect history and science, burdened with prejudices and preconceived conclusions. Unfortunately, the book also diminishes the consequences of approaching a topic for which the author did not prepare methodologically, nor did he become acquainted with the relevant works of non-Croatian authors, of whom there are few. As a consequence, Fine's approach to the topic - contrary to stated intentions - is traditionalist in its method, superficial and unreliable. It would be commendable if the author, alert to all these shortcomings, especially his attitude towards Croats and his inappropriate methodology, found the strength to publicly restrain himself from this book."
Fine has also contributed to understanding of Bosnian history, working to correct popular misconceptions, especially during the Balkan wars of the 1990s. He co-authored Bosnia and Hercegovina: A Tradition Betrayed with former student Robert J. Donia, a work published in England, the US, and in Bosnian translation in war-time Sarajevo. He traveled to and lectured in the besieged cities of Sarajevo and Mostar during the war.
