This report from HealthLeaders Media compiles early reactions and comments on the Centers for Medicare and Medicaid Services (CMS) proposed rule for Medicare Shared Savings Accountable Care Organizations (ACOs). The six executives interviewed (from Kaiser Foundation Health Plan, Geisinger Health System, Alegant Health, Dean Health System, Monarch Healthcare, and Scripps Health) all have decided not to apply to become ACOs, or are waiting for the final regulations before making a final decision whether to apply.