During the first years of organized agricultural research in Mexico in the 1940s, two agencies ran separate programs for corn improvement. The Rockefeller Foundation's Office of Special Studies and the Mexican government's Office of Experiment Stations (later called the Agricultural Research Institute) carried out research on corn with distinct aims and methods. That they differed strongly is well established in the literature. Many authors have discussed a Rockefeller Foundation program that reportedly emphasized hybrid corn, a technical choice that embodied a (...) preference for assisting wealthy farmers who could afford hybrid corn and the necessary agricultural inputs. Conversely, these authors attribute to the Mexican program a focus on open-pollinated corn, which presumably manifested its concern for Mexico's small farmers who saved seed. This article argues that the reverse was true. The Rockefeller Foundation program initially was committed to a type of improved open-pollinated corn while the Mexican program proceeded with a strict, U.S.-style hybrid program. I try to illuminate each group's priority on yield, as well as additional significant, and complicating, breeding priorities that precluded any collaboration between the two. (shrink)