To address natural resource scarcity, pollution, and other harmful effects of climate change, some scientists and policymakers emphasize the adoption of input-efficient technologies like water-saving devices and fuel-saving stoves. Proponents often refer to these input-efficient technologies as ‘win-win,’ for the benefits to their users and to the environment, and lament their low adoption rates by consumers, in what they call an ‘efficiency paradox.’ A new paper examines this paradox and finds that the benefits to consumers from input-efficiency adoption are, on average, negative.