ABSTRACTAt the turn of the 1910s, a productive tension opposed two competing kinds of North American city planning actors: urban reformers (such as Benjamin Marsh, founder of the National Conference on City Planning (NCCP) in 1909) and professional city planners (such as Frederick Law Olmsted Jr, new director of the NCCP in 1911). Analysing the many unsuccessful attempts, between 1911 and 1913, to send the ‘Cities and Town Planning Exhibition’ – a British itinerant exhibition directed by the Scottish thinker and reformer Patrick Geddes (1854–1932) – to tour America, this article examines the transnational similarities and interactions between American and European urbanist milieux; the competing scales (municipal, national, international) in this dialogue; and the strategies of the professionalization of planning.