Abstract
The paper describes, against the background of the development of documentation systems in the German outpatient (alcohol) and drug treatment field since the late 1970s, the implementation of the data sampling system COMBASS, introduced in the state of Hessen in 2000/2001. It describes some benefits and difficulties in the implementation. Documentation increased the knowledge of client characteristics, client needs and caseloads. The implementation was, on the other hand, slowed down by insufficient and unevenly distributed technical resources. Problems with the software and statistical tools decreased the compliance among counsellors as they could not benefit from the documentation work. The German example illustrates the importance for documentation systems, to be successful, to be easy to use and relevant for the work of the counsellors.