In 1784 the Congregatio de Propaganda Fide in Rome published a unique edition to celebrate the visit of King Gustav III of Sweden (1746–1792). The book contains a poem by Gudmund Jöran Adlerbeth praising the Swedish king in forty-six different languages, including seven translations into Slavic languages (Bulgarice, Dalmatice, Illyrice, Polonice, Russice, Ruthenice, Serviane) printed in three different alphabets: Latin, Glagolitic, and Cyrillic. The present paper offers a description of some linguistic features of the different Slavic texts and attempts an analysis of how these features relate to the respective language designations and script systems. Through a comparison with other polyglot editions from the late sixteenth to the early nineteenth centuries, the Slavic texts are put in a broader perspective, and their relationship to the history of Church Slavonic is discussed.