This book discusses the ideological factors and their impact upon Indonesia-Malaysia's political relations during the period 1961-1976. The ideological factors i.e. the democracy-capitalist and communist-socialist, greatly influenced the political relations between the two South East Asian countries during the bipolarity era (early Cold war period). The nature of political relations between Indonesia and Malaysia was based upon ideological factors. The changes in the political relations between Indonesia and Malaysia after 1965 was dominated by the changes in political ideology in Indonesia, i.e. from communist-socialist influences (under "old order" Sukarno) to democracy-capitalist under "new order" Suharto. The relationship between the systemic and domestic factors also discussed in this book. Domestic factors also influenced the changes ideology in Indonesia in the mid-1960s.The similar political ideology between Indonesia and Malaysia after the Indonesian Coup of September 1965 influenced the better and harmonious political relations. The ideological factors was one of the vital factors in analysing Indonesia-Malaysia political relations during the period of 1961-1976.