First nationalist political party in Indonesia to gain wide popular support.
Founded in 1912 to promote the interests of Muslim merchants, it soon began working for the self-government of the Dutch East Indies. Its religious appeal helped it grow rapidly, and by 1916 it claimed 350,000 members. As it became increasingly involved in revolutionary activities, communist elements entered the organization. A struggle for power ensued between religious leaders and communists, which culminated in the party dividing in 1921. Sarekat Islam declined after the departure of its left wing.