This article analyses employers’choice to base merit bonuses on relative performance. The relative element consists in comparing workers’output and its major advantage is to eliminate the mutual uncertainty they bear. However, bonuses based on relative performance theoretically encourage workers not to cooperate with their colleagues. Using a primary sample of 15,859 private-sector French firms in 1992, we show that bonuses based on relative performance are more likely to be chosen when output and sales fluctuate. In contrast, they are used less frequently when firms adopt an organisation of work based on task-sharing and cooperation between workers.