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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 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. Structure Who owns the practice What it means for outreach IPA Individual physicians and small practices Joint payer contracting and shared administration; members include primary care physicians and specialists Physician-owned medical group Physician partners One legal entity, so one buying group Hospital or health system group The hospital or system Purchasing usually runs through system contracts, value analysis committees, and GPOs Corporate-owned group (private equity, payer, retail) A corporate entity Procurement is set at the corporate level 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: Rank Physician Group State Number of Physicians Data Access 1 HealthCare Partners IPA New York (NY) 4,891 Explore 2 Santa Clara County IPA California (CA) 857 Explore 3 IPA of Nassau & Suffolk Counties New York (NY) 799 Explore 4 Patient Physician Network IPA Texas (TX) 519 Explore 5 Mount Auburn Cambridge IPA Massachusetts (MA) 367 Explore 6 Torrance Memorial IPA Medical Group California (CA) 352 Explore 7 Allcare IPA California (CA) 277 Explore 8 Valley Care IPA California (CA) 238 Explore 9 St. Vincent IPA Medical Group California (CA) 183 Explore 10 Lakewood IPA California (CA) 145 Explore 11 Greater Tri Cities IPA Medical Group California (CA) 130 Explore 12 Independent Emergency Physicians Michigan (MI) 109 Explore 13 Independent Hospitalists Arizona (AZ) 96 Explore 14 Santa Barbara Select IPA California (CA) 87 Explore 15 Allied Pacific IPA Healthcare City California (CA) 22 Explore 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. State Groups in this guide Notable IPAs Related Ampliz guide California 11 Hill Physicians, Brown & Toland, Santa Clara County IPA, Torrance Memorial IPA Top physician groups in California New York 2 HealthCare Partners IPA, IPA of Nassau & Suffolk Counties Largest New York physician groups Texas 1 Patient Physician Network IPA Largest medical groups in Texas Massachusetts 1 Mount Auburn Cambridge IPA Largest physician groups in Massachusetts Michigan 1 Independent Emergency Physicians Largest physician groups in Michigan Arizona 1 Independent Hospitalists Largest physician groups in 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. “The corporate takeover of physician practices continues unabated.” \u2014 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. Decision Typically made at the IPA Typically made at the member practice Payer contracts and risk arrangements Yes No Care management, quality, and analytics programs Yes Participates Claims and credentialing Yes No EHR and practice software Sometimes sets standards Yes Devices, equipment, and supplies Rarely Yes, usually the practice owner Prescribing and referrals No Yes, individual physicians 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: Here is a repeatable process for turning that<\/p>\n","protected":false},"author":13,"featured_media":5717,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2431],"tags":[],"class_list":["post-3407","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-physician-groups-by-city-and-state"],"_links":{"self":[{"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/posts\/3407","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/comments?post=3407"}],"version-history":[{"count":2,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/posts\/3407\/revisions"}],"predecessor-version":[{"id":7149,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/posts\/3407\/revisions\/7149"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/media\/5717"}],"wp:attachment":[{"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/media?parent=3407"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/categories?post=3407"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ampliz.com\/resources\/wp-json\/wp\/v2\/tags?post=3407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}