A major variable by which national educational systems may be compared is their structural differentiation, defined (1) as a process, referring to the multiplication of one structural element into two or more structurally distinct elements; and (2) as a state, referring to the number of structurally distinct elements which exist in a system at a particular point in time. Findings of the study, based on data for 1950 and 1960 from the 19 Latin American and 49 non-Western nations autonomous before 1960, generally supported two basic hypotheses: (1) The sequence of acquisition of structural elements in Latin American educational systems has tended to follow the item ranking of a Guttman scale of structural differentiation for that area, and (2) better than 50% accurate prediction of the structural elements an educational system will next acquire is possible when the system's differentiation level is known. Both alone and in conjunction with enrollment ratios, communicability, and urbanization, structural differentiation was found to be a key variable in educational system adaptiveness. Development of the scalogram is explained, supporting correlational data are tabulated, and bibliographies of source material are appended. (JK)