The core material of the collection of European importance is the old holdings of the Library of the Franciscan Monastery of Șumuleu-Ciuc and the Catholic High School of Miercurea Ciuc (formerly Șumuleu-Ciuc), which was later enriched with manuscripts, printed matter and periodicals. It also includes the archives, the so-called fragment collection and the tool kit of the Franciscan bookbinding workshop in Șumuleu-Ciuc.

The Library of the Franciscan Order of Șumuleu-Ciuc is the only medieval Transylvanian Catholic ecclesiastical library to have survived the Reformation. This library of medieval origin is the oldest and most authentic library monument of the book culture and cultural history of Szeklerland and, more precisely, of the Ciuc Seat. The composition of the holdings reflects the fact that the library in Șumuleu-Ciuc was established for practical purposes and that it was primarily organised for pastoral work. The books collected helped the Franciscans of Șumuleu-Ciuc in their missionary work among the Catholic Szekler and the Csángó-Hungarians of Moldavia.

The history of the school next to the Franciscan monastery probably dates back to the 15th century, with secondary education already being provided in Șumuleu in the second half of the 16th century. The earliest record of its books dates back to 1630, but there must have been a library for education even earlier. This small collection was probably incorporated into the monastery library. The library of the Society of St Mary of Șumuleu, founded in 1727 and which housed the best students, was also located there. The school library was first enriched by donations and later by purchases.

Manuscripts

We hold more than 280 manuscripts on parchment and paper from the 15th to 20th centuries. The oldest manuscript book in our library is Tractatus virtutum. It contains scholastic treatises, copied in 1467 in a Moldavian Catholic monastery. The voluminous Latin paper codex was used by Vicar Francis of Baia in the 15th century and later read in the Franciscan monastery of Chilia.

One of our two manuscripts from the 16th century is a parchment codex containing a Franciscan antiphonal, decorated with beautiful hand-painted monochrome and polychrome initials. The codex belonged to the library of the Moldavian Apostolic Administrator Marcus Bandinus, as its 17th-century blind-printed leather binding with wooden boards, made in the bookbinding workshop in Șumuleu-Ciuc, bears the Archbishop's coat of arms. It is also the oldest known bookplate made and decorated in Șumuleu-Ciuc.

Our manuscript archive contains the internationally known musical works of the Franciscan scholar Father Joannes Kájoni (cca. 1629/1630–1687) (Sacri Concentus, Organo-Missale, Kájoni Codex), his prayer book (Hortulus Devotionis), his calendar and his organ inscription. Other 17th-19th century manuscripts are invaluable sources of local history. Thus, the commandment books of Cașin, Ciuc, Gheorgheni, as well as the visitation records of Ciuc, Gheorgheni, Cașin, Odorhei and Three Seats, or the village registers of Ineu, give us an insight into the social and economic life of the former Ciuc Seat, and the laws of the Szekler villages.

The heyday of the Șumuleu-Ciuc Gymnasium was in the years 1720–1784. It was during this period that the famous mystery plays of Șumuleu-Ciuc were performed by the students, with new versions being written by the teachers in Hungarian and Latin and performed by the students every year. The rich manuscript repertoire of school dramas is still preserved in the Franciscan monastery in Șumuleu, with only a few 18th century plays surviving in our collection.

Prints

The works published in the first fifty years of book printing, up to 31st December 1500, are called 'incunabulum'. The almost 120 early printed books in the museum's collection come from the library of the Franciscan Friars of Șumuleu-Ciuc and place our institution among the most prestigious collections of early printed books in the country.

Our collection boasts a total of 112 prints from Hungary, Transylvania or Hungary-related from the 15th and 17th centuries, and ten unique 16th and 17th century prints. Examples include Cicero's family letters printed at Heltai (1581), a Latin-Hungarian Pauline monastic regulations printed in Venice in 1537, and a Franciscan rule published in 1699 at the Franciscan printing press in Șumuleu.

From the point of view of the history of culture, the books published by the Franciscan printing press in Șumuleu from 1676 to the end of the 19th century are also worthy of special attention. The printing house of the Friars published mainly ecclesiastical works (hymnbooks, calendars, rules of order, sermons, prayers), but also smaller works on history, law, philosophy, and several textbooks in Latin and Hungarian for the Catholic schools of Șumuleu and the region.

Bindings

Our manuscripts and printed books are not only of interest to researchers because of their antiquity, content or decoration, but also because of their unique characteristics: they are bound in artistic and museum-quality bindings, their former owners' inscriptions provide a colourful picture of the social and intellectual climate of the time, and faithfully reflect the books' journey from reader to reader. Most of the library's volumes have retained their original bindings. They have been decorated in Gothic, Renaissance and Baroque styles, with blind printing or gilding, and are the work of foreign or Transylvanian bookbinders. Our artistic bindings from the 15th and 18th centuries not only serve to protect the integrity of manuscripts and printed books and contribute to their solemnity and beauty, but also provide important information on the history of the book, its owners, users, and the place and time of its use. Our collection also includes most of the artistic bindings made and decorated in Șumuleu-Ciuc, in the bookbinding workshop of the Franciscan monastery, in the 17th and 19th centuries. The ornamental tools (scrolls, stamps, fillets) of the workshop that survive in our collection are made of copper in the 17th and 18th centuries and are priceless works.

Journals

In 1978, our museum was obliged to hand over to the County Library the more recent volumes of its antiquarian book collection and nearly 7420 periodicals. Subsequently, 36 periodicals from 1848–1944 in Miercurea Ciuc, Gheorgheni, Târgu Mureș, Sfântu Gheorghe, Cluj-Napoca and Budapest remained in our collection. The most significant are: Erdélyi Híradó (Cluj-Napoca, 1846), Ellenőr (Cluj-Napoca, 1848), Kolozsvári Híradó (1848), Kossuth Hírlapja (Pest, 1848), Székelyföld (Târgu Mureș, 1874), Székelyföld (Mureș, 1874), Székelyföld (Miskolc, 1874), 1882–1885), Székelység (Miercurea Ciuc, 1911, 1914, 1915), Csíki Hírlap (Miercurea Ciuc, 1912–1914), Csíki Néplap (Miercurea Ciuc, 1931–1944), Korunk (Cluj-Napoca, 1926–1940). Among local newspapers, the most valuable is undoubtedly Csíki Lapok, a bourgeois liberal political, economic and social weekly from 1889-1944, published in Miercurea Ciuc.

Documents

Our archival material consists of approximately 800 documents dating from the 16th to 20th centuries. Examples include six letters of noblemen, a map and a brief description of Moldavia by István Lakatos (late 17th century), a letter from the Csángó’s of the Bacău region to the county magistrate of Várdotfalva (1838 - an expression of the Csángó people's national consciousness).