Red-Green Alliancedemocratic politics, a Red-Green alliance is an alliance of socialist (or social democratic) and decentralist-ecologist (or, to chose a shorter word, green) parties. The alliance is often based on a shared suspicion of corporate capitalist institutions which the left believes to promote economic and social inequality and the ecologists believe to be exploitative of the environment.
In "First Past the Post" democracies, it is usually an agreement to retain separate means of defining policy, but commit to a common primary process which is "Red Green colorblind" and thus gives candidates from any party, committed to "Red" or "Green" political theory, an equal chance to be s/elected by progressives. In proportional representation or approval/preference voting democracies, this primary process is replaced by the official electoral process, and the elected candidates from "Red" and "Green" backgrounds agree to co-operate in the forming or criticizing of governments.
Countries in which red-green alliances have taken place include Germany, Belgium, France, The Netherlands, and Finland, where government coalitions were formed between socialist or social democratic parties and green parties, and Portugal, where they ran a joint ticket with the Communists.