Indonesian nationalism in the 20th century must be distinguished from earlier movements of protest: the Padri War, the Java War, and the many smaller examples of sporadic agrarian unrest had been "prenationalistic" movements, the products of local grievances. By contrast, the nationalism of the early 20th century was the product of the new imperialism and was part of wider currents of unrest affecting many parts of Africa and Asia. In Indonesia nationalism was concerned not merely with resistance to Dutch rule but with new perceptions of nationhood, embracing the ethnic diversity of the archipelago and looking to the restructuring of traditional patterns of authority in order to enable the creation of Indonesia as a modern state. It derived in part from specific discontents, the economic discriminations of colonial rule, the psychological hurt arising from the slights of social discrimination, and a new awareness of the all-pervading nature of Dutch authority. Important, too, was the emergence of the new elite, educated but lacking adequate employment opportunities to match that education, Westernized but retaining still its ties with traditional society.

The formation in 1908 of Budi Utomo ("High Endeavour") is often taken as the beginning of organized nationalism. Founded by Wahidin Sudirohusodo, a retired Javanese doctor, Budi Utomo was an elitist society, the aims of which--though cultural rather than political--included a concern to secure an accommodation between traditional culture and the modern world. Numerically more important was Sarekat Islam ("Islamic Association"), founded in 1912. Under its charismatic chairman, Omar Said Cokroaminoto, the organization expanded rapidly, claiming a membership of 2,500,000 by 1919. Later research suggests that the real figure was likely to have been no more than 400,000, but even with this greatly reduced estimate Sarekat Islam was clearly much larger than any other movement of the time. In 1912 the Indies Party (Indische Partij)--primarily a Eurasian party--was founded by E.F.E. Douwes Dekker; banned a year later, it was succeeded by another Eurasian party, Insulinde. In 1914 the Dutchman Hendricus Sneevliet founded the Indies Social Democratic Association, which became a communist party in 1920 and adopted the name Indonesian Communist Party (Partai Komunis Indonesia; PKI) in 1924.

By the end of World War I there was, thus, a variety of organizations in existence, broadly nationalist in aim, though differing in their tactics and immediate goals and in the sharpness of their perceptions of independent nationhood. In the absence of firm party discipline, it was common for individuals to belong simultaneously to more than one organization and, in particular, the presence of Indonesian Social Democratic Association members in Sarekat Islam enabled them to work as a "bloc within" the larger movement. The idea that the time was not yet ripe for communist parties to assume independent leadership of colonial nationalism later led the Comintern to formulate the strategy of cooperation with anti-imperialist "bourgeois" parties.

At the end of World War I the Dutch, in an effort to give substance to their promise to associate the Indonesian community more closely with government, created the People's Council ( Volksraad). Composed of a mixture of appointed and elected representatives of the three racial divisions defined by the government--Dutch, Indonesian, and "foreign Asiatic"--the People's Council provided opportunities for debate and criticism but no real control over the government of the Indies. Some nationalist leaders were prepared to accept seats in the assembly, but others refused, insisting that concessions could be obtained only through uncompromising struggle.

In 1921 the tension within Sarekat Islam between its more conservative leaders and the communists came to a head in a discipline resolution that insisted that members of Sarekat Islam belong to no other party; this, in effect, expelled the communist "bloc within," and there followed a fierce rivalry between the two for control of the grass-roots membership of the organization. The PKI, once it had committed itself to independent action, began to move toward a policy of unilateral opposition to the colonial regime. Without the support of the Comintern, and even without complete unanimity within its own ranks, it launched a revolt in Java at the end of 1926 and in western Sumatra at the beginning of 1927. These movements, which had elements of traditional protest as well as of genuine communist insurrection, were easily crushed by the Indies government, and communist activity was effectively ended for the remainder of the colonial period.

The defeat of the communist revolt and the earlier decline of Sarekat Islam left the way open for a new nationalist organization, and in 1926 a "general study club" was founded in Bandung, with a newly graduated engineer, Sukarno, as its secretary. The club began to reshape the idea of nationalism in a manner calculated to appeal to Indonesia's new urban elite. After the failure of the ideologically based movements of Islam and communism, nationalist thinking was directed to the idea simply of a struggle for independence, without any precommitment to a particular political or social order afterward. Such a goal, it was believed, could appeal to all, including Muslims and communists, who could, at least, support a common struggle for independence, even if they differed fundamentally about what was to follow. Nationalism, in this sense, became the idea that the young Sukarno used as the basis of his attempt to unify the several streams of anticolonial feeling. The ideas of the Bandung Study Club were reinforced by currents of thought emanating from Indonesian students in Holland. Their organization, reorganized in 1922 under the name of the Indonesian Union ( Perhimpunan Indonesia), became a centre of radical nationalist thought and, in the mid-1920s, students returning from Holland joined forces with like-minded groups at home.

The new nationalism required a new organization for its expression, and in July 1927 the Indonesian Nationalist Association, later the Indonesian Nationalist Party (Partai Nasional Indonesia; PNI), was formed under the chairmanship of Sukarno. The PNI was based on the idea of noncooperation with the Indies government and was thus distinguished from those groups, such as Sarekat Islam, that were prepared to accept People's Council membership. Sukarno, however, while seeking to create a basis of mass support for the PNI, also attempted with some success to work together with more moderate leaders and succeeded in forming a broadly based, if rather precarious, association of nationalist organizations.

At the end of 1929 Sukarno was arrested with some of his colleagues and was tried, convicted, and sentenced to four years' imprisonment. He was released at the end of 1931, but by then the united movement he had helped to create had begun to disintegrate. The PNI dissolved itself and reformed as Partindo. A number of other groups came to join in a new organization, the Indonesian National Education Club, known as the New PNI. While Partindo saw itself as a mass party on the lines of the old PNI, the New PNI, under the leadership of Mohammad Hatta and Sutan Sjahrir, aimed at training cadres who could maintain a continuing leadership of the movement and who could thus prevent it from being so easily immobilized by the arrest of its leaders.

In 1933 Sukarno was arrested again and exiled to Flores and later to Bencoolen (Bengkulu) in southern Sumatra. Repressive action followed against other party leaders including Hatta and Sjahrir, who were also exiled. In the later 1930s nationalist leaders were forced to cooperate with the Dutch, and such moderate parties as Parindra accepted People's Council membership. In 1937 a more radical party, Gerindo, was formed, but it considered support of The Netherlands against the threat of Nazism more important than the question of independence.

War in Europe and the Pacific changed the situation. The fall of the Indies to the Japanese onslaught early in 1942 broke the continuity of Dutch rule and provided a completely new environment for nationalist activity