The term “cooperative nationalism” is a difficult one in the Indonesian context. In the Netherlands Indies the terms “cooperation” and “non-cooperation” had a much more restricted meaning than they did, for instance, in connection with Indian nationalism. The determining factor was merely the decision whether or not to seek seats in the representative councils established by the Dutch. Although in this sense the period 1936–1942 can be called an era of cooperative nationalism in the Indies, because at that time most active nationalist parties agreed to participate in the councils, it is doubtful whether the term is very useful. The cooperating nationalists were themselves reluctant to be classified as such, and the Dutch, with whom the expression implies they were cooperating, generally regarded them as far from cooperative. To the uninitiated the term would seem to indicate that the cooperators took a more moderate, pro-Dutch stand than did the non-cooperators, and because it gives rise to such preconceptions the label may prove a hindrance. Various questions arise. What did the Indonesians and the Dutch understand by cooperation? In what way, apart from participation in the councils, did the cooperators differ from the non-cooperators? Why did the nationalists decide to “go back to cooperation” as they themselves phrased it? What did they hope to gain by the move? Why did cooperation fail to achieve results in terms of political reforms? The answers depend very largely on how the Dutch and the cooperators regarded each other. This paper will consider these problems in relation to the first and largest of the cooperating parties, Partai Indonesia Raja, or Parindra.