This work uses a set of panel data to contribute new evidence on the impacts of socioeconomic determinants on academic achievement in Chile. Socioeconomic determinants are found to have a statistically significant effect, which rises over time, on academic achievement. The evidence shows that two individuals of different socioeconomic levels (SEL) who achieve the same score in Chile's Educational Quality Measurement System (simce) in eighth grade, are separated by a gap of over 70 points on average four years later, when they sit the University Selection Test (PSU). It is concluded that in a context of great income inequality and high returns on tertiary education, academic achievement indexes throw up barriers to access to tertiary education, principally for the population of low socioeconomic level, thereby perpetuating poor income distribution.