In the late 1960s, Scandinavian scientists asserted that the long-rangeair pollution was causing serious acidification and that emissions all over Europewould have to be diminished. The prevailing view at the time was thatair pollution was a local phenomenon best handled by building high smokestacks,and the major polluting countries were opposed to spending money onprotecting areas far away in other countries. This chapter analyses how the discoveryof “acid rain” triggered the first international research projects to confirmlong-range air pollution and how, in a second phase, international negotiationsinvolving scientists, policymakers, and diplomats resulted in the Convention onLong-Range Transboundary Air Pollution in 1979. Later on, special protocolswere adopted, and the signing nations promised to decrease their emissions inaccordance with specific goals. Cold War politics played an interesting role inthe negotiations and led to an unexpected alliance between Nordic countriesand the Soviet Union.