Affordable Care Organizations are picking up steam thanks to the Affordable Care Act and because, well, they’re working. ACOs are collections of medical providers — primary care doctors, specialists, social workers, pharmacists and nurses — paid to care for a group of patients. If the group can reduce the cost of care while maintaining the patient’s health, it can keep and divide up the saving. If quality measures are not met, the group receives lower payments. In April, ACOs participating in the Medicare Shared Savings Program will accept Medicare patients. According to government estimates, at least two million will be enrolled by the end of the year. Unlike HMOs, patients in ACOs can go outside of a network and still receive reimbursement. “This is not about restricting care, but to proactively coordinate care and to ensure that the patients’ needs are met early in the process,” says Jonathan Blum, deputy administrator at the Centers for Medicare and Medicaid Services.