In many developing countries, a host of financial, institutional, and political factors hamstringconventional environmental regulation. Given these constraints, a promising strategy for controllingpollution is to promote the voluntary adoption of clean technologies. Although this strategy has receivedconsiderable attention in policy circles, empirical research on the adoption of clean technologies indeveloping countries is limited. This paper presents historical background and original survey data on theadoption of five clean tanning technologies by a sample of 137 leather tanneries in León, Guanajuato,Mexico, a city where tanneries have serious environmental impacts and conventional environmentalregulation has repeatedly failed to mitigate the problem. The analysis suggest that rather than top-downpublic-sector pressure and technical assistance, the key factor driving the adoption of clean tanningtechnologies in León is the bottom-up dissemination of information about the cost and quality benefits ofthe technologies.