This paper explores the consequences for quality of introducing yardstick competition in duopoly when a verifiable quality indicator is available. Yardstick competition can be implemented by a menu of transfers that are linear in the cost differential between the two firms and in quality. Cost- and quality incentives are stronger in larger firms when improvements are highly valued by consumers and firms can significantly influence quality. Expenditures on quality improvement can increase or decrease following the introduction of yardstick competition. The crucial factor is the likelihood ratio of productivity between the two firms, not productivity differences.