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