Inequality of access to schools of various types can be conceived in at least four different ways: (1) inequality of participation (re: national social composition); (2) inequality of utilization of intellectual potential (re: the ablest from all strata); (3) inequality of chance (re: those who desire an education, regardless of potential); (4) inequality of start (re: socioeconomic and cultural origins). Only the identification of the equality of access to education with equalization of the economic, cultural, and social conditions is free from the risks indicated by former variants of the definition. Observing the practice of the majority of countries, it can be said that the care for percentage indices according to the principle of the proportionality of participation at university-grade schools grows in direct proportion to the growing social disproportions upon which this inequality of participation depends. On the international scale, comparison of data becomes difficult because each country categorizes its schools and social groups differently. It seems reasonable, therefore, to consider a synthetic division based upon a uniform system of factor analysis that is independent of the traditional socio-professional classification (e.g., overprivileged, privileged, and underprivileged groups or groups of facilitated, regular, and impeded possibilities). (JC)