This panel examines the role of engineers, agronomists and soil scientists in projects aimed at economic and environmental modernization of three Latin American regions. All three scholars combine social history, environmental history and the history of science and technology in their work. Using examples from Mexico, Brazil and Colombia during the 19th and 20th centuries, the papers view technocrats as potentially significant agents of social reform, particularly when employed by state agencies focused on economic development. The three cases illustrate science and technology used to serve dominant and popular groups in different times and places. Agronomists’ expertise and interaction with a variety of farm workers and microenvironments often led them, in particular, to oppose development projects favored by regional and national landowning elites. However, in many cases they chose to support such projects publicly, to further their own political, professional or economic ambitions. This panel considers why technocrats adopted strategies of concession or opposition to regional and national power brokers in particular contexts, especially in debates over volatile issues like land reform.