At the periphery of the landmark June 1972 United Nations Conference on the Human Environment (UNCHE) in Stockholm, in the Skeppsholmen Annexe of the Moderna Museet, the Exhibition of People’s Technology proposed that environmental crises could be addressed through the low-tech solutions of alternative technology. Alternative Technology (AT) was a term in use since the eponymous conference at the Bartlett School of Architecture the previous February. It was a de-industrialising movement which extolled the small-scale, decentralised, labour-intensive, energy-efficient, environmentally sound and locally controlled. One of a number of UNCHE fringe events sponsored by the Swedish “PowWow” group, the Exhibition of People’s Technology was organised by the UK editors of a new magazine Undercurrents: The Journal of Radical Science and People’s Technology, launched that same year.1 In 1976, its founder Godfrey Boyle co-edited a major and widely read survey of alternative technology, Radical Technology, with Peter Harper, to whom the term “alternative technology” is attributed (Boyle/Harper 1976). Harper, a student of biology and experimental psychology, was a key organiser of the Exhibition of People’s Technology and in 1983 joined the pivotal Centre for Alternative Technology (CAT) in Wales, of which he had been a frequent visitor and occasional teacher since 1974.2 This article begins with Harper’s recollections of the exhibition and then moves to a record and discussion by Harper of its contents. It concludes with a more free-ranging conversation between Harper and design historian Simon Sadler about the exhibition’s philosophical and scientific context and implications, transcribed by Iris Xie.