The Australian Mushroom Growers Association (AMGA) has recently developed a revised marketing strategy to promote mushrooms using messages based on scientific findings about the nutrition and health consequences of regularly incorporating mushrooms into meals. This article evaluates impacts based on a test-market experiment in Tasmania. We use a difference-in-differences econometric methodology to quantify the programme-induced shifts in demand, and we use the resulting estimates in a supply and demand modelling framework to quantify the effects of promotion-induced demand shifts on prices, quantities, and measures of economic well-being. We estimate a conservative benefit–cost ratio for Tasmanian producers of 7.6:1 if they were to bear the entire cost and 11.4:1 if the programme were financed by a levy on production (or spawn). The aggregate benefit–cost ratio, including benefits to consumers is also 11.4:1. 1