Applying fixed-effects models to EULFS data on Spain from 1998 to 2006, the paper explores the effects of educational expansion on the occupational returns to education across different levels of education. We build an indicator of the positional value of education, based on the idea that the value of a given educational credential partly depends on the percentage of labour market entrants who have reached that level at the time when individuals enter the labour market -- it is higher when fewer individuals have reached it, lower otherwise. Our analysis for the Spanish case shows that the decrease in the occupational returns to education goes in parallel with the decrease in the positional value of education, but this devaluation of credentials has been stronger in general education (e.g., in humanities or social sciences university degrees, or in upper secondary general education) than in specialized education (e.g., in technical fields in the university, or in upper vocational training). We argue that the reason for this is most likely that general education provides a more diffuse signal of candidates’ skills than specialized education. We also find that this devaluation of credentials has been stronger in fields accessed by women in larger numbers in last decades.