| Rank | Name/(State) | Assets | As of Fiscal Year End Date |
| 1. | Bill & Melinda Gates Foundation (WA) | $29,153,508,000 | 12/31/05 |
| 2. | The Ford Foundation (NY) | 11,615,906,693 | 09/30/05 |
| 3. | J. Paul Getty Trust (CA) | 9,618,627,974 | 06/30/05 |
| 4. | The Robert Wood Johnson Foundation (NJ) | 9,359,361,000 | 12/31/05 |
| 5. | Lilly Endowment Inc. (IN) | 8,360,760,584 | 12/31/05 |
| 6. | The William and Flora Hewlett Foundation (CA) | 7,336,131,000 | 12/31/05 |
| 7. | W. K. Kellogg Foundation (MI) | 7,298,383,532 | 08/31/05 |
| 8. | The David and Lucile Packard Foundation (CA) | 5,788,480,930 | 12/31/05 |
| 9. | The Andrew W. Mellon Foundation (NY) | 5,586,112,000 | 12/31/05 |
| 10. | John D. and Catherine T. MacArthur Foundation (IL) | 5,490,449,000 | 12/31/05 |