The acidification problem is still an area of great concern. Many areas in the world are subject to large, in some cases increased, deposition ofacidifying substances. Scientific research has played a crucial role in the discovery and exploration of the problems as well as a basis for the development ofcontrol strategies for the more than 25 years that have passed since Svante Oden first presented his results. Even today scientific research is important as a tool for policy, most clearly observed in the effect-oriented second sulphur protocol under the Convention on Long-range Transboundary Air Pollution signed in Oslo 1994. Without a close international scientific cooperation this protocol would have never been able to develop. The 5th Conference on Acidic Deposition Acid Reign '95? should be seen in the context ofthe ongoing process to strengthen the scientific background for policy. It was therefore a great pleasure for Sweden to host the conference. It became a success in many respects. First the number ofscientists and presentations made this conference the most comprehensive ever on acidic deposition. From the organizers, we were extremely pleased to see the number of participants and contributions from countries outside Western Europe and North America. These participants turned the focus to areas showing signs ofan increased acidification problem and areas still under heavy pressure from acidic deposition. An excursion to the Czech republic prior to the conference underpinned this interest.