This thesis analyses UMNO factionalism from the perspective of the elite’s manipulation of the various modes of nationalisms. This thesis argues that UMNO factionalism, which is seemingly a power struggle between competing UMNO elites, has been significantly shaped by contesting nationalist ideologies that reflect the unresolved questions of national identity in Malaysia. These two issues, that is, nationalism and UMNO factionalism, have shaped Malaysian politics in significant ways. UMNO factionalism has been related to such major political events as the 1969 ethnic riots, the introduction of the New Economic Policy, the UMNO split in 1987 and the Reformasi (Reform) movement in 1998. Frequently, the impact of these disputes extended beyond UMNO politics and affected wider Malaysian politics. At the same time, due to unresolved questions of national identity, nationalism has occupied a central position in Malaysian political discourse. There are ambiguities regarding the relationships among the various ethnic identities and national identity and between the individual and the larger Malaysian community that enable elites to construct and manipulate nationalist ideologies. In this thesis, the conflicting nationalisms are captured by five different concepts of nationalism – ethnocultural, civic and multicultural nationalisms in one group and collectivist-authoritarian and individualistic-libertarian nationalisms in another. The Malaysian Prime Ministers have constructed nationalist ideology to define the Malaysian nation in their attempts to resolve the unresolved problems of national identity. The challengers’ arguments, to mobilise the community, mirror the community’s (negative) responses to the Malaysian Prime Ministers’ nationalist visions. In addition, the ideological arguments in the disputes extend the dispute beyond the elites, involving the community as well. Furthermore, because of the ideological conflicts, these factional disputes affect the direction of government policies in significant ways. This study shows that UMNO factional disputes have followed this pattern of ideological conflicts, although the exact contents may vary. The 1969 factional dispute was a clash between Tunku Abdul Rahman’s shift towards multicultural nationalism and its challengers’ ethnocultural nationalism. Tunku Abdul Rahman’s nationalist vision moved away from ethnocultural nationalism in pursuit of national integration. The challengers, reflecting the Malay community’s response to the Prime Minister’s vision, took a strong ethnocultural Malay nationalist stance. The successful mobilisation of the Malay community by ethnocultural Malay nationalists contributed to the policy shift towards ethnocultural nationalism in the 1970s. In the 1987 dispute, Mahathir’s economic policy, which moved away from ethnocultural nationalism, was challenged by Razaleigh’s ethnocultural nationalist argument. After the dispute, Mahathir could only mobilise the community by tactically employing the rhetoric of ethnocultural Malay nationalism. In the 1990s, Mahathir’s attempt to define the national identity of Malaysia by constructing a civic Malaysian nation, Bangsa Malaysia, relieved the tension surrounding the ambiguous national identity of Malaysia. It was facilitated by rapid economic growth that ameliorated ethnic contests over limited economic resources. However, the collectivist-authoritarian aspect of Mahathir’s nationalism raised another nationalist question concerning the subordination of individual liberty and rights to the collective community’s will and interests – a nationalism that justified his authoritarian rule. There was tension between an increasingly confident civic Malaysian society and Mahathir’s collectivist-authoritarian control of the society. The 1998 UMNO dispute was a clash between Mahathir’s collectivist-authoritarian nationalism and Anwar Ibrahim’s individualistic-libertarian nationalism. The latter attempted to mobilise Malaysian society with his nationalist position (the Reformasi movement) which was expressed in the demand for liberal political reform. After the dispute, Mahathir was able to regain lost political ground through the politics of fear. It seems, however, that the fundamental question remains unresolved. This unresolved tension between the demand for individual liberty and rights and authoritarian control by state elites is likely to shape the ideological arguments in future UMNO factional disputes.