| Solidago Foundation | |
| Soros Economic Development Fund | |
| Southwest Initiative Foundation | |
| The Springcreek Foundation | |
| Lydia B. Stokes Foundation | |
| Sundance Family Foundation | |
| Thrivent Financial for Lutherans Foundation | |
| Tides Foundation | |
| Tidwell Idaho Foundation, Inc. | |
| Trinity Grants Program | |
| US Endowment for Forestry and Communities | |
| W.K. Kellogg Foundation | |
| Washington Dental Service Foundation | |
| West Central Initiative | |
| Weyerhaeuser Family Foundation | |
| Winthrop Rockefeller Foundation | |
| Woodcock Foundation | |
| Zeron Foundation | |
|
