Slovenian is one of those European languages in which, for a long time, very little was written, and almost nothing at all in official and commercial life. Until the first half of the 19th century, by far the most represented genre was therefore the official Slovenian text of oath, intended for spoken use. The present publication is the first work to cover the entire collection of Slovenian oaths created up to the beginning of the 19th century by one particular kind of author: municipal bodies. The majority of the 36 texts included in the book first saw the light of day in just five or six Carniolian municipalities, primarily in Ljubljana (20), and only three are from the Styrian region. The texts of oath originate from a span of time with the possible extremes of 1493 and 1808. The principal aim of the publication is to present the texts themselves (with a facsimile, diplomatic and critical copy in TEI XML) with appropriate commentary, which will facilitate further study. The discussion focuses on the historical aspect: the circumstances and time of the emergence of the oath, its treatment to date, its content in brief, its role in the social environment, and its further significance in time and space.