CHA has submitted the attached comment letter to the Centers for Medicare & Medicaid Services (CMS) about its proposed rule revising the Medicare Shared Savings Program for accountable care organizations (ACOs). CHA generally supports a number of the proposed changes, but offers additional changes that will improve the engagement of hospitals in shared savings agreements. While supporting improvements to the beneficiary assignment methodology, CHA also urges CMS to adopt a prospective assignment methodology across all tracks. CHA also supports the expansion of Track 1 beyond the first three-year performance period, but opposes the reduction of the shared savings rate for participants continuing in Track 1. CHA appreciates changes to Track 2 and the addition of Track 3. However, CHA also urges CMS to consider multiple pathways that allow participants to transition to more population-based payments over time. Additionally, CHA urges CMS to make regulatory changes to allow ACOs to participate fully in patient safety organizations.