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Healthcare Insights

Top 25 ACOs by patient population

The healthcare landscape is changing, with a growing focus on accountable care organizations (ACOs) that prioritize quality care and cost-effectiveness. Organizations selling into the ACO market can maximize the impact of their efforts by prioritizing those that serve the most patients.

Keep reading for a data-driven analysis of the ACOs in the U.S. that serve the largest patient populations.

What are accountable care organizations (ACOs)?

Accountable care organizations are formal groups of physicians, hospitals, or other care providers that voluntarily work together to deliver coordinated care to a defined population of patients. ACOs are a key part of the move toward value-based care.

ACOs aim to ensure that patients—especially those living with chronic conditions—receive the appropriate care they need when they need it, while preventing unnecessary duplication of services, medical errors, and expenses.

Looking for a list of the largest ACOs in the U.S. ranked by patient population?

Using ConnectedCareView, we’ve compiled a list of the top 25 ACOs in the U.S. ranked by their total patient population, according to the most recent 12-month interval in our database.

Top 25 ACOs by patient population size

RankDefinitive IDACO nameStatePatient populationExplore dataset
1810909TMA PracticeEdge (Texas Medical Association - Blue Cross and Blue Shield of Texas ACO)TX5,000,000Explore
2842940Aetna - Childrens Hospital of Philadelphia (CHOP) ACOPA1,400,000Explore
3552289Aetna - Carilion Clinic ACOVA1,000,000Explore
4552388Capital Bluecross - Heritage Medical Group ACOPA700,000Explore
5579844Anthem Blue Cross of California - Healthcare Partners ACOCA675,000Explore
6579912Aetna - Riverside Health System ACOVA500,000Explore
7585269Horizon Blue Cross Blue Shield of New Jersey - Partners in Care ACONJ500,000Explore
8823406Aetna - Virtual Medical Group ACONJ400,000Explore
9969400BCBS Illinois - Advocate Physician Partners Accountable CareIL375,000Explore
10552285Advocatecare ACOIL375,000Explore
11553402Cigna - Banner Health Network ACOAZ350,000Explore
12969315BCBS Arizona - Banner Health Network ACOAZ350,000Explore
13577487UnitedHealthcare - Seton Health Alliance ACOTX320,000Explore
14969460HealthPartners - Northwest Metro AllianceMN300,000Explore
15578002Partners for Kids ACONY300,000Explore
16585460Blue Shield of California - EPIC ACOCA273,000Explore
17835846University Hospitals - Anthem Blue Cross and Blue Shield ACOOH270,000Explore
18947978Cigna - DeKalb Physicians Health OrganizationGA250,000Explore
191002286Caravan Collaborative Pathways (AKA Caravan Health ACO 22 LLC)TX246,471Explore
20552351Cigna - Westmed Medical Group ACONY237,000Explore
21553396OptumCare - North American Medical Management California ACOCA229,000Explore
221044880Caravan Health ACO 43 LLCMO218,605Explore
23777076Health Choice UtahUT200,000Explore
24856423Humana - John Muir Health ACOCA200,000Explore
25574791Rainbow Care ConnectionOH200,000Explore

Fig. 1 Data from the Definitive Healthcare ConnectedCareView product. ACO data is sourced from the Centers for Medicare & Medicaid Services and proprietary research. Data accessed June 2025.

Which ACO has the largest patient population?

TMA PracticeEdge, a commercial ACO based in Austin, TX, has the highest patient population at 5 million as of June 2025. Aetna-Children’s Hospital of Philadelphia (CHOP) is in second place with a patient population of 1.4 million. Coming in third place is Aetna – Carilion Clinic, a commercial ACO based out of Roanoke, VA, with a population of approximately 1 million patients.

The top 25 ACOs by patient population on the list represent nearly 15 million patients with an average population of 694,763 patients each. Of the top 25, 21 are commercial ACOs, two are Medicaid ACOs, and two are Medicare Shared Savings ACOs.

How many ACOs are there in the U.S.?

Definitive Healthcare tracks more than 1,800 active ACOs across the U.S. Our list of accountable care organizations by state highlights the states with the most and fewest ACOs.

You can also review analyses of ACOs by state, including rankings of the top ACOs in Texas and the top ACOs in Florida.

What are the different types of ACOs?

ACOs cover patients who are covered by different types of healthcare payors. The main types of ACOs are:

  • Commercial ACOs: Usually provider groups establish an accountable care payment model with a non-government payor.
  • Medicaid ACOs: Aligns providers and payors incentives with a focus on value for a Medicaid population.
  • Medicare Shared Savings Program: Requires measurement and improvement in quality and an annual certification process.

Learn more

Healthcare Insights are developed with healthcare commercial intelligence from the Definitive Healthcare platform. Want even more insights? Start a free trial today and get access to the latest healthcare commercial intelligence on hospitals, physician groups, ACOs, and other providers.