Mainwaring Archive Foundation C/O Brown Brothers Harriman Trust Co
Historical funder research: IRS Form 990-PF filings from US private foundations, showing who funded what in past years. This is not a list of currently open grant calls, and we do not track open RFPs from private foundations. From public IRS Form 990-PF filings (latest on file for this funder: tax year 2023). Coverage: tax years 2019–2025. Freshness: the IRS releases these returns 1.5–2+ years after the tax year ends, so 2025 is still partial and a funder's newest grants may not appear yet. Last updated: November 14, 2026. Filings can contain errors, so confirm current priorities and deadlines with the funder before applying.
Year 2025 is still partial because many returns have not been filed or released yet. That is a freshness issue — coverage in our dataset is tax years 2019–2025.
Only 66.7% of this funder's organizational grants could be linked to an IRS cause code.
The foundation checked the box saying it contributes only to preselected organizations and doesn't accept unsolicited requests.
- Form & materials
- Not stated
- Deadlines
- Not stated
- Restrictions
- Not stated
| Recipient | Location | Purpose (as filed) | Amount | Tax yr |
|---|---|---|---|---|
| American Philosophical Society | Philadelphia, PA | CHARITABLE CONTRIBUTION | $4,768 | 2023 |
| American Philosophical Society | Philadelphia, PA | CHARITABLE CONTRIBUTION | $33 | 2023 |
| Montana State | Bozeman, MT | CHARITABLE CONTRIBUTION | $5,000 | 2022 |
Grants to individuals are counted but not named.
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