| 1199SEIU in Williamson County, TX | AMERIGROUP in Williamson County, TX |
| APS Healthcare in Williamson County, TX | Aetna in Williamson County, TX |
| Alliance in Williamson County, TX | AmeriHealth in Williamson County, TX |
| American Behavioral in Williamson County, TX | Beech Street in Williamson County, TX |
| Behavioral Health Systems in Williamson County, TX | BlueCross and/or BlueShield in Williamson County, TX |
| CCN in Williamson County, TX | CHIPA/College Health in Williamson County, TX |
| Cascade Health in Williamson County, TX | Ceridian in Williamson County, TX |
| ChoiceCare in Williamson County, TX | Cigna in Williamson County, TX |
| ComPsych in Williamson County, TX | Corphealth in Williamson County, TX |
| Coventry in Williamson County, TX | First Choice Health in Williamson County, TX |
| First Health in Williamson County, TX | GHI/Group Health Incorporated in Williamson County, TX |
| Great-West in Williamson County, TX | Guardian in Williamson County, TX |
| HFN in Williamson County, TX | HIP/Health Plan of New York in Williamson County, TX |
| Harvard Pilgrim Health Care in Williamson County, TX | Health Net in Williamson County, TX |
| Holman Group in Williamson County, TX | Horizon Healthcare in Williamson County, TX |
| Humana in Williamson County, TX | Integrated Health Plan in Williamson County, TX |
| Interplan in Williamson County, TX | Kaiser in Williamson County, TX |
| LifeWise in Williamson County, TX | MAMSI in Williamson County, TX |
| MHN/Managed Health Network in Williamson County, TX | Magellan Behavioral Health in Williamson County, TX |
| MagnaCare in Williamson County, TX | Medica in Williamson County, TX |
| Medicaid in Williamson County, TX | Medical Mutual in Williamson County, TX |
| Medicare in Williamson County, TX | Multiplan in Williamson County, TX |
| NCPPO in Williamson County, TX | ODS in Williamson County, TX |
| Oxford in Williamson County, TX | PHCS/Private Health Care Systems in Williamson County, TX |
| PPOM in Williamson County, TX | PacifiCare in Williamson County, TX |
| PacificSource in Williamson County, TX | PreferredOne in Williamson County, TX |
| Providence in Williamson County, TX | Sloans Lake in Williamson County, TX |
| TRICARE in Williamson County, TX | TriWest0127 in Williamson County, TX |
| Tufts in Williamson County, TX | UniCare in Williamson County, TX |
| Uniform in Williamson County, TX | United in Williamson County, TX |
| VMC in Williamson County, TX | ValueOptions in Williamson County, TX |
| WellPoint in Williamson County, TX |