Harold KL Castle Foundation
The Harold K.L. Castle Foundation is a private foundation based in Kailua, Hawaii. Founded in 1962, it works to build resources for Hawaii’s future through grantmaking, convening, and sharing ideas and approaches. Its stated priorities include public education, nearshore marine conservation, climate resiliency, and strengthening Windward Oahu communities.
Harold KL Castle Foundation at a glance
In short: Harold KL Castle Foundation gave $6.9M across 106 grants in 2024 (avg $65K), mostly in Hawaii. 36% of 2024 grantees were new. Source: 2024 IRS Form 990-PF.
- Annual giving (2024)
- $6,886,001
- -8.0% vs 2023
- Grants made (2024)
- 106
- -4.5% vs 2023
- Average grant
- $64,962
- -3.7% vs 2023
- Median grant
- $25,000
- Total assets
- $171,295,453
- -1.3% vs 2023
- New grantees (estimate)
- 36% first-time grantees (29 of 80, 2024)
- Primary geography
- Hawaii (83% of itemized 2024 grant dollars)
- Latest 990 filing
- Form 990-PF, 2024 View filing
Data from IRS Form 990-PF, 2024; updated October 2026. New grantees are estimated by matching recipient names across years (methodology).
How to apply to Harold KL Castle Foundation
- Contact
Application contact: Elizabeth Murph
Mailing address: 1197 Auloa Road, Kailua, HI 96734
Phone: (808) 263-7073
Website: https://castlefoundation.org
Application details from Grantable's research on the foundation's public materials; confirm on its website before applying.
Open Grants
5 open opportunities from Harold KL Castle Foundation
Ko'olau Pilina Fund Grant
Harold KL Castle Foundation
Amount
US $3,000 - US $15,000
Deadline
Deadline not published
Nearshore Marine Resource Conservation Grant
Harold KL Castle Foundation
Amount
US $100 - US $4,000,000
Deadline
Deadline not published
Post-Secondary Transition RFP
Harold KL Castle Foundation
Amount
Varies
Deadline
Deadline not published
Who Harold KL Castle Foundation funds
How this funder distributes its grants
Top Recipients
Top 10 recipients in 2024
The largest 2024 recipient was University of Hawaii Foundation ($1.1M across 11 grants). Together the top 10 received $4.2M.
Organizations only. It also paid 4 grants to individuals ($233,272), which are not listed by name.
Grant Size Distribution
500 grants across all recorded years
The most common grant size was under $50K: 263 grants of 500 (53%).
Geographic Focus
Where this funder awards grants
The foundation says it funds organizations serving people in Hawaii and does not support organizations based outside Hawaii or projects outside the state that do not benefit Hawaii. Its stated priorities include Windward Oahu and nearshore waters around the main Hawaiian Islands. In 2024, 83% of reported grant dollars went to recipients in Hawaii, 14% to California, and 4% to the District of Columbia; percentages are rounded.
Grant Distribution by State
Share of 2024 grant dollars across all 106 itemized grants.
Cities
Is Harold KL Castle Foundation open to new grantees?
36%
first-time grantees, 2024
In 2024, 29 of 80 grantees (36%) were first-time recipients. First grants averaged $38K; repeat grants $113K. How we count
Medians: $25K first-time, $40K repeat.
- 50% of 2024 grantees were also funded in 2023. Method
- Giving held roughly steady from 2021 to 2024 (−6%). Method
- In 2024 it paid out 92% of its IRS minimum distribution (the 5% rule). Foundations have until the end of the next year to meet it. Method
Estimate from itemized grant lists in IRS Form 990-PF filings (2020–2024). Recipient names are matched across years, so a renamed or misspelled grantee can look new; grants to individuals are left out. Methodology.
Giving History
Giving Over Time
Total grant dollars and number of grants per year
From 2020 to 2024, annual grant giving ranged from $6.9M (2024) to $8.0M (2022). In 2024 it made 106 grants totaling $6.9M.
Grants by year
Grant recipients and amounts by year
| Recipient | Purpose | Amount |
|---|---|---|
| Social Finance Inc Boston, CA | Proposal to serve as Hawaii renewable learning fund manager [6086; pc] | $550,000 |
| University of Hawaii Foundation Honolulu, HI | Soar higher - support for windward oahu schools to participate as a gear up 6-16 model [5173; pc] | $529,240 |
| Hawaii Community Foundation (HCF) Honolulu, HI | Support for a second round of contributions to the holomua pooled fund whose goal is to improve marine resources management in Hawaii through a suite of efforts built on four pillars: place-based planning, pono practices, monitoring, and protection & restoration [5905; pc] | $500,000 |
| Kuaaina Ulu Auamo (Kua) Kaneohe, HI | To support and strengthen this critically important backbone organization and its three community-driven networks for ocean management in Hawaii. [5598; pc] | $500,000 |
| Hawaii Community Foundation (HCF) Honolulu, HI | Pilina Fund 2.0 [5618; PC] | $400,000 |
| The Nature Conservancy of Hawaii Honolulu, HI | Advancing community-based marine management to reach 30x30 goals [5660; pc] | $280,000 |
| University of Hawaii Foundation Honolulu, HI | To extend windward community college's groundbreaking hoolei scholarship that ensures all public school graduates in the koolau region can afford to attend community college [6140; pc] | $214,286 |
| Hawaii Hospital Education and Research Foundation (Hherf) Honolulu, HI | To retrofit doe classrooms for healthcare pathways in partnership with Hawaii 3r's, g70 and Hawaii pacific health [6363; pc] | $150,000 |
| University of Hawaii Foundation Honolulu, HI | Hawaii P-20 Core Support 2022-2025 [5465; PC] | $150,000 |
| Windward School District Kaneohe, HI | To internally drive windward doe schools towards aina aloha mindset achievement through teacher professional development (PD) days and closer engagement between schools and aina-based education organizations. [6371; gov] | $150,000 |
Ready to take the next step with Harold KL Castle Foundation?
Financial History
Multi-year comparison from IRS filings
| Filing year | Total Assets | Revenue | Expenses | Grants paid | Grants | Qualifying Distributions | Net Investment Income | Distributable Amount |
|---|---|---|---|---|---|---|---|---|
| 2024 | $171,295,453 | $8,283,293 | $10,627,064 | $6,886,001 | 106 | $8,758,237 | $7,046,551 | $9,515,391 |
| 2023 | $173,491,448 | $11,327,617 | $10,879,744 | $7,485,951 | 111 | $9,503,881 | $10,105,204 | $8,920,185 |
| 2022 | $173,044,264 | $8,125,647 | $11,246,442 | $8,009,541 | 77 | $9,746,584 | $6,568,148 | $9,315,597 |
| 2021 | $177,025,059 | $18,251,388 | $10,723,568 | $7,346,190 | 100 | $9,137,911 | $17,439,780 | $9,941,270 |
| 2020 | $169,285,564 | $7,463,574 | $10,925,699 | $7,224,372 | 106 | — | $6,076,823 | $8,964,584 |
Under IRS private-foundation payout rules, Harold KL Castle Foundation reported a distributable amount of $9.5M for 2024 — the minimum it must pay out in qualifying distributions.
Research compiled by Grantable AI from public sources. Last updated October 2026.
Mission & Focus Areas
The foundation’s 2025 mission includes improving access to high-quality education from prekindergarten through college; restoring nearshore ocean areas; supporting the cultural legacy, people, and natural resources of Ko’olau Oahu communities; and strengthening communities’ ability to adapt to climate change. It also describes support for a limited number of other compelling opportunities in Hawaii.
Its stated grant priorities are public education redesign and enhancement (pre-K–12), nearshore marine resource conservation around the main Hawaiian Islands, climate resiliency, and strengthening the communities of Windward Oahu. The foundation says it occasionally funds outside these areas at its discretion, but such grants are increasingly rare and initiated by the foundation.
Eligible applicants include Hawaii-serving 501(c)(3) public charities and public schools. The foundation says it primarily funds specific projects, not ongoing general expenses, with limited exceptions for organizations it considers critical to its strategies. It does not consider proposals from individuals or businesses, or for items such as endowments, annual fund drives, sponsorships, special events, vehicles, or computers. Capital needs are considered less frequently and should be discussed with program staff before an application is prepared.
Examples among its grantees include the University of Hawaii Foundation, whose stated mission is to connect donors’ passions with University of Hawaii aspirations through fundraising and investment management for the university and people of Hawaii. The Hawaii Conservation Alliance Foundation says it supports the capacity-building and native ecosystem and biocultural conservation work of the Hawaii Conservation Alliance. Center for Tomorrow’s Leaders describes its mission as engaging, equipping, and empowering Hawaii’s future leaders through high school-level training and resources.
Grantmaking
In filing year 2024, the foundation reported 106 grants totaling $6,886,001. Grant amounts ranged from $500 to $550,000, with a median of $25,000.
Among the larger 2024 grants were $550,000 to Social Finance Inc. for a proposal to serve as Hawaii Renewable Learning Fund manager; $529,240 to the University of Hawaii Foundation for support for Windward Oahu schools participating in a GEAR UP 6-16 model; $500,000 to Hawaii Community Foundation for a second round of contributions to the Holomua Pooled Fund; and $500,000 to Kuaaina Ulu Auamo to support its ocean-management backbone organization and community-driven networks. Other reported awards included $400,000 to Hawaii Community Foundation for Pilina Fund 2.0, $280,000 to The Nature Conservancy of Hawaii for community-based marine management, and $214,286 to the University of Hawaii Foundation to extend the Hoolei Scholarship.
The foundation’s website says prospective applicants begin with an online inquiry. New applicants are asked to contact Beth Murph first; returning grantees are directed to discuss their idea with their program officer before starting a new application. New prospective applicants need their organization’s 501(c)(3) tax ID number. Staff review inquiries on a rolling basis and say they will contact applicants within one month to request more information or explain that support cannot be considered because of limited resources or a mismatch with priorities. The filing lists the application materials, deadlines, and award restrictions as being in an attachment, but those details are not provided here.
The foundation also lists a Windward Youth Leadership Grant program with awards of $500–$5,000 for youth-driven service projects benefiting a group, organization, or place in Windward Oahu. Its program description advises allowing at least six weeks for grant processing, not including the project period.
Leadership & Key People
Leadership team and compensation from IRS filings
The 2024 filing lists Henry M. D’Olier as director and chairman, and Dr. Claire L. Asam, Dr. Kittredge A. Baldwin, Corbett A.K. Kalama, Dee Jay A. Mailer, James H. McIntosh, Jennifer G. Sabas, T. Aulani Wilhelm, and Eric K. Yeaman as directors. Carlton K.C. Au is listed as vice president of finance.
Harold KL Castle Foundation is led by Terrence R. George, President & CEO on every filing since 2020; 6 of 15 officers listed in 2024 are compensated.
Officers on the 2024 filing
Terrence R. George
President & CEO
On filings since 2020
40 hrs/week
$372K (2020) → $415K (2024)
Henry M. D'olier
Director & Chairman
On filings since 2020
2 hrs/week
No compensation reported
Claire L. Asam
Director
On filings since 2020
0.5 hrs/week
No compensation reported
Corbett Ak Kalama
Director
On filings since 2020
0.5 hrs/week
No compensation reported
Dee Jay A. Mailer
Director
On filings since 2020
0.5 hrs/week
No compensation reported
Eric K. Yeaman
Director
On filings since 2020
0.5 hrs/week
No compensation reported
James H. McIntosh
Director
On filings since 2020
0.5 hrs/week
No compensation reported
Kittredge A. Baldwin
Director
On filings since 2020
0.5 hrs/week
No compensation reported
Jennifer G. Sabas
Director
On filings since 2023
0.5 hrs/week
No compensation reported
T. Aulani Wilhelm
Director
On filings since 2023
0.5 hrs/week
No compensation reported
Alexander Harris
Vice President of Programs
On filings since 2020
40 hrs/week
$228K (2020) → $222K (2024)
Carlton Kc Au
Vice President of Finance
Vice President, Treasurer & CFO → Vice President of Finance, 2023
On filings since 2020
8 hrs/week
$104K (2020) → $55K (2024)
Susan L. Sumida
Secretary
On filings since 2020
5 hrs/week
$21K (2020) → $28K (2024)
Dennis Eric Co
Vice President of Resiliency
On filings since 2022
40 hrs/week
$203K (2022) → $223K (2024)
Ann S. Matsukado
Treasurer
On filings since 2023
40 hrs/week
$98K (2023) → $189K (2024)
Data from IRS Form 990 filings, 2020–2024. "On filings since" is the earliest filing we hold that lists the person; hours are average hours per week as reported.
Compensation Overview
From 2024 IRS filing
The highest reported compensation on the 2024 filing was $415K, to Terrence R George (President/CEO). 6 officers or directors reported compensation on that filing.
Frequently asked questions about Harold KL Castle Foundation
How much does Harold KL Castle Foundation give each year?
Harold KL Castle Foundation gave $6.9M across 106 grants in 2024, according to its 2024 IRS Form 990-PF. In 2023 it gave $7.5M across 111 grants.
What is Harold KL Castle Foundation's typical grant size?
Harold KL Castle Foundation's median grant in 2024 was $25,000, and its average grant was $64,962, across 106 grants on its 2024 IRS Form 990-PF. Organizations receiving their first grant from Harold KL Castle Foundation that year got $38K on average.
Where does Harold KL Castle Foundation give grants?
Harold KL Castle Foundation gives mostly in Hawaii: 83% of the grant dollars itemized on its 2024 IRS Form 990-PF went to recipients there. The next largest state was California (14%). The most frequent recipient cities were Honolulu, HI (54 grants), Kaneohe, HI (10 grants), Kailua, HI (8 grants) and Washington, DC (4 grants).
Does Harold KL Castle Foundation give general operating support?
Occasionally: 2% of Harold KL Castle Foundation's 2024 grants with a stated purpose (2 of 106) were for general or operating support, per its 2024 IRS Form 990-PF.
Who are Harold KL Castle Foundation's largest grantees?
Harold KL Castle Foundation's largest 2024 grantees include University of Hawaii Foundation ($1,115,551 across 11 grants), Hawaii Community Foundation (HCF) ($960,000 across 4 grants) and Social Finance Inc ($550,000), according to its 2024 IRS Form 990-PF. It also paid 4 grants to individuals ($233,272), which are not listed by name. Together they received 38% of its itemized 2024 grant dollars.
How large is Harold KL Castle Foundation?
Harold KL Castle Foundation reported $171.3M in total assets on its 2024 IRS Form 990-PF. It paid out $8.8M in qualifying distributions that year, against a required minimum of $9.5M (roughly 5% of its investment assets). Falling short in one year is not a violation: foundations have until the end of the next year to meet the minimum.
What does Harold KL Castle Foundation fund?
The foundation’s 2025 mission includes improving access to high-quality education from prekindergarten through college; restoring nearshore ocean areas; supporting the cultural legacy, people, and natural resources of Ko’olau Oahu communities; and strengthening communities’ ability to adapt to climate change. See mission & focus areas ↑
How do I apply for a grant from Harold KL Castle Foundation?
Harold KL Castle Foundation has no public application process in the sources Grantable reviewed. Check castlefoundation.org for current guidelines, or contact the foundation directly before submitting a request.
What is Harold KL Castle Foundation's EIN?
Harold KL Castle Foundation's EIN (Employer Identification Number) is 99-6005445. IRS Form 990 filing data is available on this page for 2020–2024.
Data last updated October 2026. Sourced from IRS Form 990-PF filings. Research dossier generated October 2026.
Data update history
(1)
When this profile's IRS filing data changed on Grantable
- IRS filings on file for fiscal years 2020–2024
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Cite this profile
Grantable. (2026). Harold KL Castle Foundation funder profile. GrantGraph. Retrieved October 19, 2026, from https://grantable.co/funders/harold-kl-castle-foundation-morg_34ca0a403e9c4d138510829a11827b99
BibTeX
@misc{grantable_996005445_2026,
author = {{Grantable}},
title = {{Harold KL Castle Foundation funder profile}},
howpublished = {GrantGraph},
year = {2026},
url = {https://grantable.co/funders/harold-kl-castle-foundation-morg_34ca0a403e9c4d138510829a11827b99},
note = {Accessed 2026-10-19. Data licensed CC BY 4.0}
}The figures on this page are open data under CC BY 4.0: reuse them with credit to Grantable and a link. Download the data.
Figures come from Harold KL Castle Foundation's IRS filings (methodology). AI-written summaries, news items and logos are not covered by the open licence. Spot an error? Email hello@grantable.co.
Harold KL Castle Foundation down — hundreds of funders to go?