The European Coal and Steel Community, or ECSC, was one of the three European Communities (along with the European Community and Euratom) that now comprise the "first pillar" of the European Union. It was the earliest precursor of the modern EU. The basic idea behind the ECSC, as defined by French foreign minister Robert Schuman in 1950, was simple: several countries would pool their coal and steel resources, so that no country would be able to sustain war against another within the community.

There were originally six states in the ECSC: France, Germany, Italy, Belgium, the Netherlands, and Luxembourg. These states formed most of the core elements of the EU under the auspices of the ECSC, including an Assembly (now the European Parliament), a High Authority (now the European Commission), a European Court of Justice, and a Council of Ministers (now the Council of the European Union). Later, these institutions were expanded to cover the other European Communities.

The ECSC treaty had a lifespan of fifty years. It was not renewed following its expiration, mostly because its provisions had been duplicated by other EU treaties.