This article by Brian Urquhart, originally in the form of a Memorial Lecture for Lord Caradon, discusses the opportunities and challenges as well as the problems of the post-Cold War world. It suggests the magnitude and urgency of these problems-political, environmental or population-related-and proposes ways of tackling them, especially through the updating and strengthening of the United Nations. Improvements in the United Nations peace and security system as well as its capacity for dealing with global problems are discussed and the author stresses the urgent need for progress towards a regime of international law.