While survey data supports a strong relationship between personality and labour market outcomes, the exact mechanisms behind this association remain unexplored. We take advantage of a controlled laboratory set‐up to explore whether this relationship operates through productivity. Using a real‐effort task, we analyse the impact of the Big Five personality traits on performance. We find that more neurotic subjects perform worse, and that more conscientious individuals perform better. These findings suggest that at least part of the effect of personality on labour market outcomes operates through productivity. In addition, we find evidence that gender and university major affect this relationship.