Foreword. Abridged summary. Introduction (G.J. Heij). The first two phases of the Dutch Priority Programme on Acidification (DPPA). The third phase of the DPAA. Organizational and financial aspects of DPPA-III. The content of the final report. References. Emission, concentration and deposition of acidifying substances (J.W. Erisman, A. Bleeker). Introduction. Emissions. Concentrations. Depositions. Source contributions and origin of the deposition. Relations between atmospheric deposition and throughfall. Uncertainties. Deposition originating from natural sources and comparison of the Dutch situation with other European countries. Conclusions and gaps in current knowledge. References. Effects on forest ecosystems (L.J. van der Eerden). Introduction. Laboratory-scale manipulation experiments. Effects at stand scale. Effects at regional scale. Effects on other biotic components of the forest ecosystem. Critical levels and critical loads. Discussion. Conclusion. References. Effects of atmospheric deposition on non-forest ecosystems in The Netherlands (R. Bobbink, J.G.M. Roelofs , J.M. Verstraten). Introduction. Terrestrial ecosystems. Aquatic ecosystems. Critical loads. References. Summary and conclusion (G.J. Heij). Trends in emissions, concentrations and depositions. Effects on forest ecosystems. Effects on non-forest ecosystems. Curative measures. Evaluation and synthesis.