Svetlozar Eldurov's book "Catholics in Bulgaria: 1878-1989" is the first ever comprehensive study of that period in the history of the Catholic community in Bulgaria. The work is based on extensive archival research and is comparable in scope to Prof. Lyubomir Miletich's ethno-linguistic studies written a hundred years ago.

The monograph traces the historical development of the community in four periods: from the Liberation in 1878 to the First Balkan War in 1912, between 1912 and 1918, between the two World Wars, and under the totalitarian regime. The author chronicles the specifics of the two Latin-rite dioceses, Sofia-Plovdiv and Rousse-Nikopol, described by Eldurov as the "showcase" of the Catholic Church in Bulgaria, and the Byzantine-rite Apostolic Exarchate of Sofia, which takes its origins from the Uniates. After the pinnacle reached by the Catholic community in the 17th c. with the diplomatic missions of Archbishop Peter Parchevich (1643), the first Bulgarian printed book, Abagar, produced by Bishop Philip Stanislavov in 1651, and the Chiprovtsi Uprising in 1688, the history of Bulgarian Catholics advanced to a new height in the early 20th century, with the prestige of the French Catholic colleges, the "Bulgarian decade" of Archbishop Angelo Roncalli (later on Pope John XXIII) as apostolic visitator in Sofia (1925-1934), and the martyrdom of Catholic clergy at the dawn of the communist regime.

Eldurov explains in his book that most of the literature since the start of the 20th century has viewed Catholics as alien and damaging to Bulgarian national unity. Along with the other religious denominations, Catholicism has long been just a subject of study for the purposes of scientific atheism. After November 10, 1989, the subject of Catholics gained popularity in connection with the fresh disclosures of the crackdown on them under communism.