The causes and consequences of acid rain are subjects of considerable concern, controversy, and confusion. The effects of acid deposition on the chemistry of lakes and streams, and on the survival of fish and other aquatic life, have been greatly clarified by the results of the recent Anglo-Scandinavian research programme. A concise, non-specialist account of the results, their interpretation, and implication is here presented by the Director of the programme.The book includes chapters on emissions, transport, and deposition of acid pollution; hydrochemical studies in catchments; catchment process studies; catchment manipulation experiments; the role of hydrology and soil chemistry; palaeolimnological studies; the toxic effects of acidification on fish and other aquatic life; and catchment modelling studies.The highly interdisciplinary nature of the research will appeal to a wide range of scientists and to policy-makers interested in acid rain and its consequences. It will also be useful for postgraduates and third-year first degree students in the environmental sciences.