This paper investigates the impact the publication of firm-specific data has on the competitiveness of experimental oligopoly markets. We compare two treatments: in one, firms are informed about their rivals’ actions and profits. In the other, firms are only given aggregate information about their rivals’ actions (average quantities or prices). We find that more information leads to more competition. In the treatment where aggregate information is given, we confirm the theoretical result that Bertrand markets are more competitive than Cournot markets.