The negative consequences of dual labour markets have been extensively documented, but so far little attention has been paid to their effects on workers’ on-the-job training and cognitive skills. This column discusses evidence from PIAAC – an exam for adults designed by the OECD in 2013. Temporary contracts are associated with a reduction of 8–16 percentage points in the probability of receiving on-the-job training, and this training gap can explain up to half of the gap in numeracy scores between permanent and temporary workers.