Quakers have maintained offices at the United Nations in New York and Geneva almost since the beginning of the UN system in 1945. While much work by Friends in the cause of peace is local, Friends have long understood that real change towards a more just, peaceful and sustainable world also requires effort at the international level. The 'quiet diplomacy' and other approaches of the staff teams at Quaker United Nations Office (QUNO) in Geneva and New York, and in other parts of the UN system, have been important over the decades of the life of QUNO in the evolution of norms, practices and institutions at the international level on a broad range of concerns to Friends. In this Backhouse Lecture, David Atwood draws on more than sixteen years of experience of QUNO work in Geneva to look at Quaker witness at the UN 'from the inside out'. In something of a 'nuts and bolts' account, Atwood explores such questions as how decisions are made about what issues to work on; tensions that shape choices; and other dimensions and dynamics intended to help Friends to know better the nature of the work done in their name at the UN. He draws especially on his own experience as QUNO-Geneva's Representative for Disarmament and Peace to shed light on some key lessons about the ongoing nature of this style of Quaker engagement. Through several case histories, Atwood demonstrates how it is possible to make a difference, and that considerable change is possible. While confirming his belief in the continuing relevance of Quaker UN work, Atwood concludes by pointing to a number of realities which, in his view, will be important for the future sustainability of that work. In particular, he offers a challenge to Friends to consider the nature and adequacy of our structures for managing that work. He also raises the question: how capable are we as Friends to find that core message for our era, behind which Friends could unite and speak and act globally, with one voice?