The Saarland University and State Library (Saarlaendische Universitaets- und Landesbibliothek SULB) runs the Special Subject Collection Psychology which is part of an information system for the supra-regional literature supply in Germany. With the increasing opportunities for electronic information the following question emerged for the Special Subject Collection: how can a contribution to the availability and preservation of electronic documents particularly with regards to grey literature be made? Giving an answer SULB established the repository PsyDok in autumn 2002. PsyDok is one of the few subject-specific digital repositories in Germany. It is a registered data provider of the Open Archives Initiative (OAI) and certified by the German Initiative for Networkinformation (DINI), which developed a variety of standards digital repositories have to comply with to achieve this mark of quality. PsyDok offers many interfaces to disciplinary and multidisciplinary retrieval and information systems. The allocation of Uniform Resource Names (URN) guarantees persistent availability and citeability of the documents. Several services and mechanisms guarantee not only a maximum of visibility and a rapid and global scientific exchange and flow of information stored on PsyDok but also its long term availability and its scientific utilization. PsyDok fits the principles of "Open Access": Many different document types may be published, but PsyDok focuses particularly on diploma theses, dissertations, professorial dissertations and grey literature.