Bismarckian health systems are mainly governed by social health insurers, but their role, status, and power vary across countries and over time. We compare the role of health insurers in three distinct social health insurance systems in improving health systems' efficiency. In France, insurers work together as a single payer within a highly regulated context. Although this gives insurers substantial bargaining power, collective negotiations with providers are highly political and do not provide appropriate incentives for efficiency. Both Germany and the Netherlands have introduced competition among insurers to foster efficiency. However, the rationale of insurer competition in Germany is unclear because contracts are mostly concluded at a collective level and individual insurers have little power to influence health system efficiency. In the Netherlands, insurer competition is substantially more effective, but primarily focused on price and cost containment. In all three countries, the role of insurers has been transforming slowly to respond to common challenges of assuring care quality and continuity for an ageing population. To assure sustainability, they need to ensure that care providers cooperate with the same quality and efficiency objectives, but their capacity to do so has been limited by insufficient support to enforce public information on provider quality.