The Union of Public Libraries (predecessor of today’s Slovenian Public Libraries Association) was founded on 27 February 1992 in Bled. In 1993 and 1994, a systematic partnership with IZUM (Institute of Information Science, an autonomous public institution since 1992, with its predecessor from 1990) was already formed. At the time, the Board of Directors of the Union requested the conversion of local systems (VIR, ATLASS, MOL, STEVE) into the national COBISS system, which became the foundation of a long-term partnership. Public libraries as the largest segment of the network actively contribute to the shared COBIB.SI database (central national catalogue within the COBISS system), ensure uniform cataloguing and book lending, and participate in testing and developing the system. In its second decade of operating, its cooperation with IZUM strengthened significantly as COBISS3 was being implemented. The Slovenian Public Libraries Association coordinated working groups, education and feedback from the field, which helped adapt the new system to the needs of public libraries. In the third decade, the Association evolved into a more active participant – the COBISS Ela platform (2024), which was developed under the Slovenian Public Libraries Association initiative, is a good example. Hence, public libraries are more than just users and have been playing a key role in creating the COBISS system since its very beginning. This partnership – spanning from the foundations of a unified information infrastructure in the 1990s to the modern digital solutions – shows a successful model of public cooperation, which considerably improved knowledge accessibility and the status of public libraries in the Slovenian society.