Based on Swedish register data from 2003 to 2012, this study attempts to explain over-education and upward mobility among tertiary graduates. Rarely used explanatory factors are central in the analyses, such as 'still in study' and 'field of education'. Tertiary graduates in low-wage jobs are regarded as over-educated. The results of this work suggest that the general increase in graduates correlates well with the increase in over-educated graduates. Many of those who were categorised as over-educated were students, and graduates from some specific fields were particularly vulnerable to working in low-wage jobs. Sixty per cent of the graduates found more suitable jobs, while up to 40 per cent stayed in jobs related to lower wages. Graduates from fields associated with higher risks of over-education were also less likely to experience upward mobility. The increasing occurrence of over-education among graduates may not only result in a substandard utilisation of human capital (and absence of social mobility), it also seems that the presence of large numbers of over-educated graduates in low-paid work may have implications for unskilled workers, through displacement effects.