This paper analyzes the activities, members, and effects of an inter-American expert network for the diffusion of psychometric knowledge, specifically of standardized aptitude testing for university admission in Latin America during the 1960s and 1970s. Within the framework of educational transfer studies, the role of international, nongovernmental, and philanthropic organizations is examined. It is argued that circulation of psychometric knowledge and technologies led to a new governing regime for learning and learners. The paper discusses the effect of convergence and Americanization, in the context of US-promoted "Alliance for Progress," but also of divergence and resistance.