This report traces the origin and expansion of the Association of Credit and Rural Assistance (ACAR) in Minas Gerais, Brazil, from the late 1940s to 1960. Created as a joint project between the American International Association (AIA) and the Minas Gerais state government, I highlight how ACAR became a site where international and Brazilian planners adopted rural extension as a method to pursue agricultural transformations. Rural extension provided planners and their cohort of experts a vehicle to convey technology and know-how to farmers in Minas Gerais. While planners and technocrats often critiqued the results of their programmatic efforts, they consistently valorized rural extension over the course of a decade.In the early 1950s, ACAR's infrastructure rapidly expanded in Minas Gerais. Yet, short-term commitments between the AIA and the Minas Gerais state government caused friction over strategies to promote economic development. Renewed political and economic commitment by both parties in the mid-1950s provided longer-term stability. Further, in 1956, Brazil's federal government launched the ACAR model semi-nationally, endorsing the institution's approach to promote agrarian change. This political decision coincided with the standardization of rural extension and the support for access to credit contracts as common practice across the national network. By the late 1950s, ACAR's initial aims of improving the lives of farming families and improving home economics markedly shifted towards increasing agricultural productivity. In doing so, rural extension offered state planners a malleable method to promote science and technology to intensify farm production, while avoiding calls for large-scale land reform.