The research presented is concerned with the analysis of the Vlašim castle library aiming to contribute to the knowledge on a significant Czech landscape garden from the second half of the 18th century. Another objective was to verify what information this source can provide for research into the field of architectural and historical development of garden art monuments. The catalogue of the castle library in Vlašim was studied based on four main criteria – date of publishing, author, the topic of the publication together with specific features of the printed edition. With these aspects, the books that could be related to the creation and development of the garden have been selected. This relationship was further investigated at the interpretation stage, when relations between selected books and the garden were searched for as well as its relation to the development of garden art in Europe. It was found that the library contains publications by the leading philosophers of the Enlightenment as well as books dedicated to horticulture and garden art. The dedications on the flyleaves of some books support the theory that the founder of the garden was Prince William I of Auersperg. Other findings indicated a possible connection with the anglo‑chinois garden prototypes at Monceau and Ermenonville. The found inventory of plants drafted by Antonín Hoborský provided the opportunity to observe a new line of information leading to possible relations to the residence in Herrenhausen, Germany. Based on the findings, it is possible to conclude that surveys of castle libraries can offer a range of important information, and should become a standard part of the architectural and historical surveys of garden art monuments.