Largest Independent Physician Groups in the US: IPA List by State (2026)

Last updated on October 8th, 2026

The largest independent physician groups in the US are independent physician associations (IPAs): networks of physician-owned practices that contract with health plans together. Hill Physicians Medical Group in Northern California reports more than 6,000 physicians, the highest count we could confirm from a primary source. A 2023 Becker’s ranking put HealthCare Partners IPA in New York at 4,891, and Brown & Toland Physicians reports more than 3,000.

This guide ranks the largest IPAs with a source and year on every number, shows which states they cluster in, and explains how independent practice is changing. It then walks through how healthcare sales and marketing teams can build target lists of independent practices and the people who run them.

Key Takeaways

• Hill Physicians Medical Group reports 6,000+ physicians, and California is home to 11 of the 17 groups listed in this guide.
• No national registry ranks IPAs. Counts are self-reported or come from third-party rankings, so treat them as directional and confirm before quoting one in a pitch.
• Independent practice is shrinking: 42.2% of physicians were in private practice in 2024 (AMA), and 82.0% were employed by hospitals or corporate entities as of January 2026 (PAI and Avalere).
• IPA leaders typically negotiate payer contracts and run shared services, while member practices usually still own their equipment and staffing decisions. Sellers need to reach both audiences.
• The most reliable way to reach independent groups is to filter by practice ownership and group size, then match practices to IPA directories by NPI, rather than buying a list of IPA names.

What Counts as an Largest IPAs in the US?

An independent physician association is a network of independent doctors or small practices that contract with payers together while each keeps ownership of its own practice. IPAs are the structure behind most “largest independent physician group” rankings, but they are not the only form of independent practice.

IPA leadership usually handles payer contracting, claims, credentialing, and care management for members. Brown & Toland Physicians lists each of those services on its physician support page.

List of Top 15 Largest Independent Physician Groups in the US by State

Below is a curated list of the largest independent physician associations in the US, based on physician count and regional influence:

For the full picture across all ownership types, see our guides to the largest physician groups in the United States and the largest physician groups by state.

Counts matter less than location, so here is where these groups cluster.

Which States Have the Largest Independent Physician Groups?

The Independent practice association list of California has the most. Of the 17 groups named above, 11 are in California, 2 in New York, and 1 each in Texas, Massachusetts, Michigan, and Arizona.

If your territory is California, you have the deepest pool of IPA-level accounts. Outside it, independent practice is more often a collection of single-specialty groups and small practices, so ownership and group-size filters matter more than IPA names.

Before building a list, it helps to know how fast this segment is changing.

How Many US Physicians Are Still Independent?

Fewer than half, by either of the two main measures. The AMA’s 2024 Physician Practice Benchmark Survey found 42.2% of physicians in private practice, down from 60.1% in 2012. The PAI and Avalere 2026 report found 82.0% of physicians employed by hospitals or corporate entities as of January 1, 2026. The two studies measure different things (practice ownership versus employment), but both show the independent segment shrinking.

• Group size: 47% of physicians worked in practices of 10 or fewer physicians in 2024, the first time that share fell below 50%, and 6.5% described their practice as private equity-owned.
• Practice ownership: hospitals and corporate entities owned 63.9% of practices in 2026, and there were 81,100 fewer physician-owned practices than in 2018 (PAI and Avalere).
• Why it is happening: AMA survey respondents pointed to payment pressure, high resource costs, and administrative burden as the drivers. Negotiating better payer rates together is the original reason IPAs exist.

“The corporate takeover of physician practices continues unabated.” — Kelly Kenney, CEO, Physicians Advocacy Institute. Source: PAI and Avalere 2026 report

For sellers, the practical point is that an IPA roster ages quickly. A group that listed a practice last year may have lost it to a health system since, which is why contact data needs regular re-verification. For the health-system side of the market, see our guide to the largest health systems in the USA.

Independent groups are shrinking, but the ones that remain hold real buying influence.

Why Independent Physician Groups Matter to Healthcare Sellers

Independent groups combine payer-level decisions at the IPA with practice-level buying at the member. Knowing which decision sits where tells you whom to contact first.

Medicare Advantage raises the stakes for the IPA-level column. 55% of eligible Medicare beneficiaries (35.2 million people) are enrolled in Medicare Advantage in 2026, and IPAs that take on risk are scored on quality and cost. That makes care-management, analytics, and quality vendors natural fits for IPA leadership.

Who to prioritize depends on what you sell:

• Healthtech and health IT: the IPA’s chief medical officer or medical director for network-wide programs, and practice administrators for tools each practice adopts.
• Pharma and life sciences: IPA quality and pharmacy leaders, plus high-volume prescribers in member practices.
• Medical devices: practice owners in the specialties that perform your procedure, since they sign the purchase order.
• Hospitals and health systems: independent groups in your market that may be open to partnership, using primary care physician and specialty lists to size each group.

Here is a repeatable process for turning that into a target list.

How to Find and Target Independent Physician Groups

Start with practice ownership and group size, not IPA names. IPA names tell you who the umbrella is; ownership and size filters tell you who actually buys.

1. Define the segment

Specify specialty, state, and group size, for example “independent cardiology practices with fewer than 10 providers in Texas.” Pull the number of doctors in the US by specialty to size the opportunity, and the physician groups by specialty guide for group-level context.

2. Separate owners from employed physicians

Owners decide on equipment and software; employed physicians usually do not. Filter for private practitioners and practice owners so you do not spend outreach on physicians with no purchasing authority.

3. Map practices to IPAs

Most large IPAs publish a provider directory, such as Hill Physicians’ provider listings and Brown & Toland’s Find a Doctor tool. Match directory entries to your list by NPI, which is the cleanest shared identifier. If you only have NPIs, the NPI Lookup turns them into practice and contact profiles.

4. Choose titles deliberately

For IPA-level programs, target the chief medical officer, medical director, and network operations leads. For practice-level purchases, target practice owners, administrators, and office managers.

5. Enrich and verify before sending

Upload your mapped list for enrichment and confirm emails and phones are current. A list built from a 2023 roster will contain practices that have since left their IPA.

6. Measure by segment

Track bounce rate, reply rate, and meetings booked separately for IPA-level and practice-level contacts. Compare results by state and specialty to see where independent practice converts best, then put your next round of effort there.

Action items for this week: pick one specialty and one state, pull the practice-owner segment, and match 20 practices to their IPA directory by NPI. That small test shows you how much of your current list is already out of date.

Common mistakes

• Treating an IPA’s headcount as an employed roster. Members are separate businesses.
• Sending one message to IPA leaders and practice owners. They care about different outcomes.
• Building from a static list. Ownership changes, such as Brown & Toland joining Altais, are not reflected in older rankings.
• Ignoring group size. A 4-physician practice and a 60-physician group buy differently.

Build Your Independent Physician Groups by State With Ampliz

Ampliz gives you access to 6.8M+ healthcare providers and 11M+ healthcare executives, with records re-verified every 30 days and credits returned for any contact you flag as incorrect. For this segment, four features do most of the work:

• HCP Lookup: filter by specialty and sub-specialty, practice ownership (owners versus employed physicians), private practitioner versus hospital-based, and number of providers per practice.
• Physician Group Views: search physician groups by name, specialty focus, size, and geography, and see each group’s provider roster and administrative contacts.
• Executive Search: find practice managers, administrators, and medical directors at physician groups by title, seniority, and facility type.
• Data Enrichment Engine: upload the NPIs or names you matched to IPA directories and get verified emails, phone numbers, and LinkedIn profiles back in minutes.

Sales teams can use these filters to build territory lists, and marketing teams can segment the same lists for campaigns. See how Ampliz sources and verifies its data.

See independent practices in your territory. Book a demo to run a practice-ownership and group-size search for your specialty and state. Book a Demo

FAQs:

What is the largest independent physician group in the US?

Hill Physicians Medical Group in Northern California reports more than 6,000 physicians, the highest count we could confirm from a primary source. No national registry ranks IPAs, and counts are self-reported, so the order can shift with how each group counts contracted specialists. A 2023 Becker’s ranking put HealthCare Partners IPA in New York at 4,891.

How many US physicians still work independently?

It depends on the definition. The AMA’s 2024 survey found 42.2% of physicians in wholly physician-owned private practices. PAI and Avalere report that 82.0% of physicians were employed by hospitals or corporate entities as of January 2026, leaving about 18% in physician-owned settings. Both measures show independent practice shrinking.

What is the difference between an IPA and a medical group?

An IPA is a network of separately owned practices that contract with payers together. A medical group is usually a single entity whose physicians work under shared ownership, held by physicians, a hospital, or a corporate investor. Some organizations combine both: Brown & Toland includes an IPA network and an employed physician group.

Do IPAs make purchasing decisions for their members?

Usually not for the practice itself. IPA leadership negotiates payer contracts and runs shared services such as claims, credentialing, and care management, while member physicians keep ownership of their practices and typically buy their own equipment and software. Map who decides what before choosing a contact.

How can I find contact details for decision-makers at independent physician groups?

Start with ownership and group-size filters to find independent practices, then match them to IPA directories by NPI. Ampliz’s HCP Lookup and Physician Group Views support that workflow, and the Data Enrichment Engine returns verified emails and phones for an uploaded list. Records are re-verified every 30 days.

Conclusion

The largest independent physician groups are concentrated in California, led by Hill Physicians and Brown & Toland, with large IPAs in New York, Texas, and Massachusetts. Their counts are self-reported and shifting, and the independent segment as a whole is shrinking, so a list of IPA names is a starting point rather than a target list. Reaching these groups well means separating IPA-level decisions from practice-level buying, filtering by ownership and size, and re-verifying contacts before every campaign.

If you sell into independent practices, Ampliz can help you build that list. Book a demo to see practice-ownership, group-size, and specialty filters applied to your territory, with verified contacts ready for outreach.

Book a Demo

Subbu

V. SubramanyamHead of Product at Ampliz | Healthcare Data & GTM Intelligence Expert
V. Subramanyam is the Head of Product at Ampliz, where he leads the strategy and development of healthcare data intelligence solutions that help sales, marketing, recruiting, and commercial teams identify and engage healthcare decision-makers across the United States.
With extensive experience in product management, healthcare data, B2B SaaS, GTM strategy, and sales intelligence, he focuses on building products that simplify healthcare prospecting through accurate physician, hospital, executive, and healthcare organization data. His work emphasizes data quality, enrichment, and AI-powered workflows that enable organizations to make faster, data-driven decisions.
Connect with Him:

LinkedIn: https://www.linkedin.com/in/vsubramanyam
Company: https://www.ampliz.com