Research network and database system - a distributed environment for collaborative work Thomas Burch and Ansgar Schmitz University of Trier / Germany In this paper, we present the design and implementation of a completely Tcl/Tk-based client/server application, which is intended to support a large community of reseachers whithin a so-called "Sonderforschungsbereich". The main purpose of this distributed system is to enable the participating users to cooperate via the internet in creating and annotating their data. On the client's side, it provides a graphical user interface, which comprises components for user accounting, data import, data classification, workflow management, group management, data retrieval and finally online publication. On the server side, it is connected to a relational database management system. The communication between client and server is done with the help of socket commands within Tcl/Tk. The advantage of this bidirectional and synchronized connection is that the user can be immediately informed about a change of data in his area of interest. This avoids data redundancies and enables a large group of users to effectively establish a commonly used pool of information. Besides Tcl/Tk, we use several additional libraries such as bwidgets, CoST, mysqltcl and tcllib.