This paper uses data from the 1970 Birth Cohort Study in the UK to explore the well-established link between "liberal" social values and education. Whilst the link itself is well-established, the underlying mechanism is not; the paper explores empirically mechanisms that have been proposed for this link. In particular it considers the effects of social background, "ability", personal efficacy and field of study on social values to explore both direct and indirect effects of education. The paper finds that, whilst there are important effects of social background and ability on social values, these do not explain the effect of educational attainment. Moreover, differences according to field of study suggest that the most likely mechanism linking education with liberal values is one of socialisation.