ntegrating Open Source Library Systems Name of presenters: Theodor Tolstoy, Andreas Hedström Mace Theodor Tolstoy is Head of Development at Stockholm University Library. Andreas Hedström Mace works as a librarian and project manager at Stockholm University Library, whose main focus of 2015 is managing an implementation of Koha at the library. Abstract Stockholm University Library has chosen to replace its current library system with the free and open source library system Koha. The idea is that Koha will serve as the circulation module in a larger system architecture for printed material , where the Swedish union catalogue LIBRIS as well as the internally developed book logistics system Viola are key components. These three are all open systems, even though all are not open source. Specifically Viola is not there yet , but work is in progress towards that goal, while it is also being implemented at the Linnaeus University Library. With open source soft ware the library’s dependence on proprietary providers for business-critical systems is reduced, and allow s greater control over data and software. There are challenges however with such an approach; specifically regarding how to build a consistent and coherent system architecture, which integrates the various systems with one another using open API:s. There are also several data – and workflows that can and probably will change in the process of integrating Koha with the other systems. This presentation aims to present the work being done at Stockholm University Library, while also discussing the benefits of opening up the library systems to others.