The Communist Party of Indonesia was a communist party in the Dutch East Indies and later Indonesia. It was the largest non-ruling communist party in the world before its violent disbandment in 1965. The party had two million members in the 1955 elections, with 16 percent of the national vote and almost 30 percent of the vote in East Java. At the time, it was the largest communist party in the world after the Chinese and Soviet communist parties.
During most of the period immediately following the Indonesian Independence until the eradication of the PKI in 1965, it was a legal party operating openly in the country. Accused of responsibility for the 1965 army-led coup attempt, the party was banned by General Suharto in March 1966 and its members were violently purged.