The eleven papers presented in this issue are intended to provide a comprehen sive description of the cloud systems studied during the Kleiner Feldberg experi ment. The first paper provides a general overview of the experiment and a summa ry of the main accomplishments. The following three papers then describe the cloud systems from the meteorological, microphysical and chemical perspectives. Another four papers address more specifically the issues of incorporation of aerosol particles and trace gases within cloud droplets. A synthesis of the Kleiner Feldberg cloud properties and a comparison with experimental data is then provided by a paper which models the airflow and cloud mycrophysics and chemistry for selected cloud episodes during the experiment. Deposition of trace substances via cloud interception with the vegetation is the subject of the next paper, which integrates experimental data in a deposition resistance model. A technical paper at the end of the issue reports on a newly developed holographic technique to measure cloud droplet size distribution, which was tested for the first time during this experiment. The collaborative nature of the work accomplished within GCE is emphasized by the large authorship of most papers presented in this issue. This should not be regarded with surprise, but rather as an indication of the interdisciplinary efforts of the GCE scientific community for the accomplishment of this study. SANDRO FUZZI Coordinator, EUROTRAC sub-project GCE Journal of Atmospheric Chemistry 19: 3-35, 1994. 3 © 1994 Kluwer Academic Publishers. The Kleiner Feldberg Cloud Experiment 1990.