This paper demonstrates that shared control, which occurs when multiple controlling shareholders have veto power over business decisions, protects minority shareholders while preserving valuable private benefits of control. Disagreements among controlling shareholders prevent them from undertaking projects that, although in their collective interest, inefficiently harm minority shareholders. The same disagreements may block efficient investment decisions, though. By solving this trade-off, we show that the likelihood that shared control is efficient increases with three firm characteristics: overinvestment problems, costs of verifying cash flows, and financing requirements. The model contrasts shared control and monitoring, providing testable implications on the role that large shareholders play in corporate governance.