'Ibis volt.nne contains the proceedings of a \\Orkshop on "Acid Deposition" held on September 9, 1982 at the Reichstag in Berlin. 'Ibe \\Orkshop was organized within the frame\\Ork of project COST 61a bis* of the Commission of the European Communities (CEC), as a satellite meeting to the joint meeting of WOrking Parties 4 (Pollutant Cycles) and 5 (Transport and Modelling - Field Experiments) which was held on September 7 - 8 at the Federal Environmental Agency in Berlin. 'Ibe organisation of the scientific \\Orkshop programme was in the hands of a CEC Acid Deposition Task Force consisting of nine scientists actively participating in projects COST 61a or COST 61a bis: Beilke (Federal Republic of Germany), Brosset (Sweden), Elshout (The Netherlands), Graven- horst (France), Liberti (Italy), ott (CEC, Belgium), Penkett (United Kingdan), Sandroni (CEC, Italy) and Zephoris (France). 'Ibe \\Orkshop progrcmne consisted of the presentation and discussion of five invited review papers covering different areas of the acid deposition problem and of ongoing \\Ork on topics which are relevant to acid depo- sition. Emphasis was placed on new scientific ideas and on indicating the most important areas of uncertainty, including the specification of a series of key research needs in the field of acid deposition. 'Ibis was done out of concern for danage to forest and freshwater ecosystems in various European regions attributed at least in part to acid deposition originating fran air pollution.