On June 24, 2010, CMS is holding a Special Open Door Forum provider call on the Medicare Shared Savings Program/Accountable Care Organizations (ACOs).   The call will focus on the formation and use of ACOs to enhance the quality and efficiency of physician services. CMS will solicit comments from physicians, physician associations, hospitals, consumer groups, and other interested parties on:  joint accountability among providers in the formation and use of ACOs; cost and quality measures to assess performance; risk adjustment; attribution of Medicare beneficiaries to ACOs; benchmarks for purposes of defining shared savings; coordination with other value-based purchasing initiatives; and Medicare beneficiary protections.