The presence of libraries in social media platforms that mostly based on interaction, sharing, and engagement can contribute to the identification of user expectations as well as service delivery and marketing. In this regard, the content produced by libraries on social media platforms and the reaction data obtained from users can be utilized for impact assessment purposes. In this study, it is aimed to describe user interaction and to detect the content categories by analyzing the Facebook public page contents of public libraries in Ankara. Accordingly, 1739 posts and the interaction data related to these posts were collected on the Facebook pages of 10 public libraries in Ankara. The collected data were firstly presented with descriptive statistics, and then the posts were analysed by using text mining applications. Additionally, topics and sub-topics are detected. The results showed that specific libraries actively use their Facebook pages. It was also revealed in the study that the post contents in the event category were mostly for children and students at primary and secondary levels. The number of posts included in the collection category was lower than the number of posts in other categories. It is recommended in the study that the analyzed public libraries should develop more content according to their target audiences. It is also emphasized that the analyzed libraries should increase the number of post interactions, and they should increase the number of posts related to collections and services. Lastly, It was emphasized that the analyzed libraries should act in the context of a social media strategy to increase user interaction and provide its sustainability.