National behaviour is purposive: it seeks to attain certain goals. Governments pursue goals in both national politics and international relations. The Foreign Service bureaucracy advises government on the best "fit" between political goals, national resources and international limitations, and tries to implement specific policy decisions made by government. Success in trade diversification in turn served to embolden questions regarding the premises of New Zealand defence and foreign policy which had remained unchanged although the world political situation had altered fundamentally by the 1970s. The cornerstone of New Zealand's foreign policy at present is the Australia, New Zealand and the United States alliance. Public opinion can have an important role to play at election time in defining the boundaries of permissible foreign policy behaviour, and in constraining the latitude of governments even between elections. The chapter also presents an overview of the key concepts discussed in this book.