Digitization of cultural heritage and of the scholarly record is often described as a collective effort, where contributions from many institutions are needed. No single institution can ever hope to digitize every resource available. In practice, however, this aspect of cooperation often comes second, years after institutions have started (and sometimes also closed down) individual digitization projects. The process of building cooperation is difficult, but will in the long run be equally or even more important than building individual archives.Sweden has a long tradition of cooperation between academic libraries. In the early 1970s, the National Library and the academic libraries started building LIBRIS [1], a cooperative union catalogue which is today used by hundreds of Swedish libraries ranging from small museums to big universities. The history if LIBRIS show that cooperation among many institutions is difficult, but that in the long run, everybody gains from it. It provides interesting learning-lessons on how to build and maintain a joint library cooperation. In the history of LIBRIS there are endless examples of controversy, disagreement and delay, but also of vision, leadership, and constructive dialogue. Today, LIBRIS is maintained and developed by the National Library of Sweden, and participation is free for Swedish libraries, both public and academic. However, the most important aspect of LIBRIS is the collective work being done by the participating libraries. LIBRIS started as a project for digitizing the production of library catalogues, but is today an important node also for cooperative digitization of library collections. The obvious reasons for this are that LIBRIS holds a lot of the bibliographic metadata used in digitization projects, and that it is a well-known service where the public finds information about library resources. Possibly, however, the most important role of LIBRIS is as a platform for conversation between libraries – a system everybody knows, works with, and has opinions about.Another important collaboration project is DiVA [2], Academic Archive On-line, where today 29 Swedish and one Norwegian university have succeeded in building and maintaining a system for academic publications. Development of DiVA began in the year 2000 and today it's an established institutional repository and publication database. DiVA provides a way of sharing the costs of developing and maintenance. Perhaps the most important aspect of DiVA is that it has given many of the smaller university colleges access to a system they would not have been able to afford, had they been working alone. DiVA is built on open source technology and the technical maintenance is done by the Uppsala university library.During fall 2009, the National Library of Sweden invited all Swedish research libraries running digitization processes to participate in a process to collectively procure digitization robots. In may 2010, five big university libraries together with the National Library decided to enter into a framework agreement with Treventus GmHB.The benefits of a joint procurement process turned out to be much larger than the contribution from the actual digitization robots. By working closely together, the process has resulted in a number of advantages for all participating libraries, some expected while others where unexpected. Naturally, the framework agreement resulted in a lower unit cost than if the libraries had initiated individual procurement processes. Other advantages stem from use of both identical hardware and software, e.g. support and exchange of knowledge.More unexpected was the large increase in momentum among the libraries. Since no library wanted to be the last to purchase a digitization robot, the process to obtain money was greatly accelerated. The momentum was further increased by cooperation around workflows for production, metadata management, OCR, and long-term preservation. The collaborative approach as well as the open-source model technical infrastructure from DiVA is now serving as a model for a common repository for digitized special collections, images, books, provenances and archival records. The system, today going under the working name Alvin [3], will be linked to the bibliographic records in LIBRIS.In a small country such as Sweden, collaboration is crucial for long-term sustainability of digitization projects. Beginning with LIBRIS, Swedish academic libraries have achieved something that might be described as a “habit to cooperate”. This habit sometimes has the negative side effect of libraries waiting for someone to initiate cooperation, rather than start working. However, the benefits of actively seeking cooperation are huge. There are many lessons to be learned from 40 years of cooperation, such as how to allow and acknowledge differences between organizations and projects, in collective government and decision-making, in the difficult process of initiating cooperation in new areas, and in the shared learning process that comes from working together. Perhaps the most important, but also most difficult, lesson is the process of going from collective discussion to cooperative working.