Harold K L Castle Foundation
Historical FunderKailua, Hawaii · EIN 99-6005445 · Private foundation · Website
Grants paid (2024)$6.7M
Organizations funded106
Typical grant$25,000
Total assets$199.5M
Half of its grants to organizations were between $12,500 and $60,000.
From the return
How to apply
The foundation filed the following application information (Form 990-PF Part XV, tax year 2024):
| Contact | ELIZABETH MURPH |
|---|---|
| Address | 1197 AULOA ROAD, KAILUA HI 96734 |
| Phone | 8082637073 |
| Form and materials | SEE STATEMENT 14 - ATTACHMENT |
| Deadlines | SEE STATEMENT 14 - ATTACHMENT |
| Restrictions | SEE STATEMENT 14 - ATTACHMENT |
Copied as filed. Deadlines on a tax return describe the foundation's usual process; they are not confirmation of a current open cycle.
What it funds
Share of grant lines on the latest return, classified from the purpose each grant states.
Where it gives
8% of grants went outside Hawaii.
Grants paid in tax year 2024
| Recipient | Location | 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… | $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… | $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… | $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… | $150,000 |
| Purple Maia | Aiea, HI | For the expansion of halau hekili, a middle college high school on the campus of windward community college. [6277; pc] | $145,000 |
| Hawaii Conservation Alliance Foundation | Honolulu, HI | For the next phase of the ahupuaa accelerator, a program to expand watershed-wide community management that has expanded to 46 partners… | $132,715 |
| Resources Legacy Fund | Sacramento, CA | To help advance the holomua initiative and the care for aina now coalition (formerly green fee) environmental capital formation work [6125;… | $120,000 |
| The American Ai Forum Aka Ai Education Project | San Francisco, CA | To deliver professional development that helps hawaii public school teachers better understand artificial intelligence (ai) and how to… | $115,000 |
| College Summit Inc Dba Peerforward | Washington, DC | To scale a promising peer counseling model to four additional high schools. [6267; pc] | $103,163 |
| C&c of Honolulu Office of Climate Change Sustainability and Resiliency | Honolulu, HI | To help the honolulu city & county optimize its climate adaptation work aligned with the foundation's new climate strategy [5860; gov] | $100,000 |
| Hawaiian Islands Land Trust (Hilt) | Honolulu, HI | To continue to work in close partnership with the trust for public lands to secure priority lands for community use and aina aloha mindset… | $100,000 |
| New Teacher Center | Santa Cruz, CA | To work alongside the hawaii department of education in building the support and resources that enable complex area leaders to bring… | $100,000 |
| Conservation International Foundation | Honolulu, HI | Puulau project: a two-year effort to combine additional knowledge bases from fishers and community with wester-science based monitoring… | $95,000 |
| Koolau Foundation | Kaneohe, HI | Catalyst funding to develop the haiku valley cultural preserve [5907; pc] | $75,000 |
| Kualoa-Heeia Ecumenical Youth Project (Key) | Kaneohe, HI | To bolster response to the little fire ant in koolauloa and koolaupoko through grassroots community education, training, monitoring, and… | $75,000 |
| The Pacific American Foundation (Paf) | Kaneohe, HI | For the launch of an esports development program in windward oahu schools [6127; pc] | $75,000 |
| College Summit Inc Dba Peerforward | Washington, DC | Peers leading peers through higher education [5516; pc] | $70,000 |
| 50Can | Washington, DC | Core organizational support for hawaiikidscan, an education advocacy organization committed to ensure that hawaii has an excellent and… | $67,500 |
| Public Schools Hawaii Foundation | Honolulu, HI | To launch a new effort that combines human and artificial intelligence to expand student support by offering more personalized navigational… | $67,500 |
| Center for Tomorrow's Leaders | Honolulu, HI | To strengthen the persuasive communication and writing of the roughly 300 high school students served each year [6368; pc] | $60,000 |
| Hawaii Alliance of Nonprofit Organizations | Honolulu, HI | To help nonprofits engage in policy, work with data to develop clearer outcomes, and develop stronger revenue streams [6378; pc] | $60,000 |
| Hawaii Chamber of Commerce Foundation | Honolulu, HI | To support employer collaboratives that help ensure students in hawaii are on clear pathways to high skill, high wage, in-demand careers… | $60,000 |
| Hawaii Workforce Pipeline | Kailua, HI | To forge stronger connections between windward employers and public school students in the region. [6282; pc] | $55,340 |
| Collaborative Support Services | Honolulu, HI | General operating support for the commit to keiki initiative to educate candidates and elected officials about the importance of investing… | $50,000 |
| Collaborative Support Services | Honolulu, HI | Building a community-based early childhood continuum in the waimnalo community of oahu [5605; pc] | $50,000 |
| Hawaii Chamber of Commerce Foundation | Honolulu, HI | Unsolicited challenge grant to hawaii chamber of commerce foundation to support business relief fund to help businesses affected by the… | $50,000 |
| Hawaii Community Foundation (Hcf) | Honolulu, HI | Support to ensure appropriate administration of the maui strong fund's current and expected grant expenditures totaling $192.6 million in a… | $50,000 |
| Hawaii Executive Collaborative | Honolulu, HI | Support for the rediscovering hawaii's soul initiative to create spaces where leaders from all sectors could have candid, difficult… | $50,000 |
| Hui Malama O Ke Kai Foundation | Waimanalo, HI | E hoakoakoa: a community & educational space [5166; pc] | $50,000 |
| Leadership Instituue Hawaii Department of Education | Aiea, HI | Laying the foundation for middle level education magic:strengthening public middle schools in hawaii [5920; gov] | $50,000 |
| Manoa Heritage Center | Honolulu, HI | Sam cooke endowed fund [4463; pc] | $50,000 |
| Risehi Foundation | Kailua, HI | To support middle school youth in their development and career exploration. [6278; pc] | $50,000 |
| The Coral Reef Alliance | San Francisco, CA | To work with a coalition of partners to catalyze cesspool conversions at a meaningful scale sufficient to meet the states 2050 goal for… | $50,000 |
| The Nature Conservancy of Hawaii | Honolulu, HI | To continue their decades-long work with communities and the state on maui and hawaii island, as well as initiating new work on kauai… | $50,000 |
| Wastewater Alternatives and Innovations | Honolulu, HI | To lead state and non-profit partners in improving the way we manage water quality in hawaii as part of the holomua initiative [5854; pc] | $50,000 |
| University of Hawaii Foundation | Honolulu, HI | Develop a malama aina plan for moku o loe that grounds it in its cultural heritage and guides it through the changing climate ahead [5586;… | $49,335 |
| University of Hawaii Foundation | Honolulu, HI | To ensure each doe district has a strong regional intermediary partner for work-based learning and to build a new data and accountability… | $46,450 |
| Hawaii Electricians Training Fund | Honolulu, HI | Interim credential pre-apprenticeship program & recruitment expansion [6065; nc] | $40,000 |
| Hi Fusioned (Isis Hawaii) | Honolulu, HI | To move key elements of coding education and career pipelines forward, including teacher training and career exposure/mentorship,… | $40,000 |
| Project Vision Hawaii | Honolulu, HI | To provide free hearing screenings for youth as a complement to project vision hawaii's already successful vision screening program,… | $40,000 |
| River of Life Mission | Honolulu, HI | Support to strengthen and expand river of life's new distributed hub model of serving windward oahu's homeless population to transition… | $40,000 |
| University of Hawaii Foundation | Honolulu, HI | Honolulu community college (honcc) summer cte academy (2024, 2025) [6021; pc] | $40,000 |
| Vibrant Hawaii | Hilo, HI | To develop a network of resilience hubs across windward oahu [6275: pc] | $40,000 |
| Hui O Ko'olaupoko | Kailua, HI | To increase coordination, response, and community involvement to fight the invasive species little fire ant in koolaupoko, with a focus on… | $37,500 |
| Malama Learning Center Corp | Honolulu, HI | To produce another eight segments for local popular cable show outside hawaii that humanizes dlnr and socializes the intentions and actions… | $31,500 |
| Hawaii Department of Education Ocid-Extended Learning Branch | Honolulu, HI | Support for hawaii department of education complex area teams to coordinate student-led student transition activities to and from middle… | $30,000 |
| College Promise | Washington, DC | To review and provide feedback on the hawaii promise initiative [6252; pc] | $25,000 |
| Hawaii Afterschool Alliance | Honolulu, HI | To support a developmental evaluation of the community schools model in twelve participating public schools [5870; pc] | $25,000 |
| Hawaii Executive Collaborative | Honolulu, HI | Support of 2024 hawaii executive conference [6385; pc] | $25,000 |
| Hawaii Local2030 Hub | Honolulu, HI | To allow hawaii green growth to continue to populate the state's 2030 sustainability goals dashboard and to spur action to achieve these… | $25,000 |
| Hawaii Workforce Funders Collaborative | Kapaau, HI | For the hawaii workforce funders collaborative (hwfc) to cover membership dues that support the operative budget of this new organization… | $25,000 |
| Kanu Hawaii | Honolulu, HI | Pledge to our keiki: a tie-off grant to help kanu hawaii build on the pledge to our keiki platform to cement its department of education… | $25,000 |
| Khm International | Kaunakakai, HI | Malama e lua loko i'a: support for ka honua momona to restore their two adjacent fishponds on moloka'i with priority on the makaha of ali'i… | $25,000 |
| Malama Maunalua | Honolulu, HI | To help advance the holomua initiative by better aligning pro-fishing perspectives with those of government agencies, community groups, and… | $25,000 |
Showing the 60 largest of 106 grants to organizations.
Grants approved for future payment
| Recipient | Location | Purpose | Amount |
|---|---|---|---|
| Social Finance Inc | Boston, HI | Proposal to serve as hawaii renewable learning fund manager [6086; pc] | $550,000 |
| The Nature Conservancy of Hawaii | Honolulu, HI | To continue their decades-long work with communities and the state on maui and hawaii island, as well as initiating new work on kauai… | $550,000 |
| 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… | $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… | $500,000 |
| Manoa Heritage Center | Honolulu, HI | Sam cooke endowed fund [4463; pc] | $400,000 |
| University of Hawaii Foundation | Honolulu, HI | Soar higher - support for windward oahu schools to participate as a gear up 6-16 model [5173; pc] | $264,620 |
| 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… | $225,000 |
| University of Virginia | Charlottesville, VA | Provide the good jobs hawaii project team with a learning and evaluation partner that can offer actionable insights and ongoing analysis of… | $191,186 |
| Hawaii Conservation Alliance Foundation | Honolulu, HI | For the next phase of the ahupuaa accelerator, a program to expand watershed-wide community management that has expanded to 46 partners… | $150,000 |
| 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 |
| Paepae O Heeia | Kaneohe, HI | Serving as fiscal sponsor for koolau aina aloha, to support their collective impact goals and specifically support the second phase of… | $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… | $150,000 |
| College Summit Inc Dba Peerforward | Washington, DC | To scale a promising peer counseling model to four additional high schools. [6267; pc] | $121,822 |
| Hawaii Community Foundation (Hcf) | Honolulu, HI | Support to ensure appropriate administration of the maui strong fund's current and expected grant expenditures totaling $192.6 million in a… | $100,000 |
| Hawaii Community Foundation (Hcf) | Honolulu, HI | Pilina fund 2.0 [5618; pc] | $100,000 |
| Vibrant Hawaii | Hilo, HI | For vibrant hawaii to scale successful early work and establish a network of community-based climate resilience hubs in koolau. [6480; pc] | $100,000 |
| Purple Maia | Aiea, HI | For the expansion of halau hekili, a middle college high school on the campus of windward community college. [6277; pc] | $87,000 |
| New Teacher Center | Santa Cruz, CA | To work alongside the hawaii department of education in building the support and resources that enable complex area leaders to bring… | $80,000 |
| 50Can | Washington, DC | Core organizational support for hawaiikidscan, an education advocacy organization committed to ensure that hawaii has an excellent and… | $67,500 |
| Hawaii Workforce Pipeline | Kailua, HI | To forge stronger connections between windward employers and public school students in the region. [6282; pc] | $55,339 |
| Hawaii Executive Collaborative | Honolulu, HI | Support for the rediscovering hawaii's soul initiative to create spaces where leaders from all sectors could have candid, difficult… | $50,000 |
| Jim Saunders Fund | Kailua Kona, HI | An unsolicited grant award of $50,000 to the jim saunders fund in honor of james C. mcintosh to support the education and well-being of… | $50,000 |
| The Coral Reef Alliance | San Francisco, CA | To work with a coalition of partners to catalyze cesspool conversions at a meaningful scale sufficient to meet the states 2050 goal for… | $50,000 |
| Project Vision Hawaii | Honolulu, HI | To provide free hearing screenings for youth as a complement to project vision hawaii's already successful vision screening program,… | $40,000 |
| Hui O Ko'olaupoko | Kailua, HI | To increase coordination, response, and community involvement to fight the invasive species little fire ant in koolaupoko, with a focus on… | $37,500 |
| Hilo High School | Hilo, HI | Support for post-high student transitions [6447; gov] | $35,000 |
| Kailua High School | Kailua, HI | Support for post-high student transitions [6451; gov] | $35,000 |
| Kapolei High School | Kapolei, HI | Support for post-high student transitions - huakai pono: guiding kapolei's youth toward their future [6454; gov] | $35,000 |
| Kealakehe High School | Kailua Kona, HI | Support for post-high student transitions and stronger senior capstone projects [6475; gov] | $35,000 |
| Molokai High and Intermediate School | Hoolehua, HI | Support for post-high student transitions [6448; gov] | $35,000 |
| Waikea High School | Hilo, HI | Support for post-high student transitions for waiakea graduates [6465; gov] | $35,000 |
| Malama Learning Center Corp | Honolulu, HI | To produce another eight segments for local popular cable show outside hawaii that humanizes dlnr and socializes the intentions and actions… | $30,000 |
| Hawaii Afterschool Alliance | Honolulu, HI | To support a developmental evaluation of the community schools model in twelve participating public schools [5870; pc] | $25,000 |
| Hawaii Chamber of Commerce Foundation | Honolulu, HI | To support employer collaboratives that help ensure students in hawaii are on clear pathways to high skill, high wage, in-demand careers… | $25,000 |
| University of Hawaii Foundation | Honolulu, HI | Core operating support that allows the uh economic research organization to more effectively engage with decisionmakers on important policy… | $25,000 |
| Center for Tomorrow's Leaders | Honolulu, HI | To strengthen the persuasive communication and writing of the roughly 300 high school students served each year [6368; pc] | $20,000 |
| Connected the National Center for College and Career | Berkeley, CA | Provide support to connected: the national center for college and careers to design, test and launch the first phase of a community of… | $20,000 |
| Hawaii Alliance of Nonprofit Organizations | Honolulu, HI | To help nonprofits engage in policy, work with data to develop clearer outcomes, and develop stronger revenue streams [6378; pc] | $20,000 |
| Hawaii Department of Education Ocid-Extended Learning Branch | Honolulu, HI | Support for hawaii department of education complex area teams to coordinate student-led student transition activities to and from middle… | $20,000 |
| University of Hawaii Foundation | Honolulu, HI | Investing in teachers, honoring student voices: the hawaii writing project young writers camp [pc; 6243] | $12,500 |
| Collaborative Support Services | Honolulu, HI | General operating support for the commit to keiki initiative to educate candidates and elected officials about the importance of investing… | $10,000 |
| Seeqs Foundation | Honolulu, HI | A one-time grant in support of seeqs public charter school to establish the "seeqs sharing hub" as a center of professional development and… | $9,000 |
| Hawaii Education of the Arts Inc (Hearts) | Honolulu, HI | Wylf youth grant: hearts kupuna concerts [6473; pc] | $5,000 |
| Lutheran Church Missouri Synod | Kaneohe, HI | Wylf youth grant: leaders of tomorrow: inspiring others to become a healthy community through farm-fresh ingredients [6403; pc] | $3,200 |
Giving by year
| Tax year | Grants paid | Grant lines |
|---|---|---|
| 2024 | $6,685,968 | 152 |
| 2023 | $7,332,479 | 168 |
Sources
- IRS Form 990-PF, tax year 2024, filed Nov 14, 2025 - IRS e-file batch, object ID 202543179349104159
- IRS Tax Exempt Organization Search for EIN 99-6005445
- Profile updated Nov 4, 2026
Facts on this page come from the foundation's own IRS Form 990-PF filings as published by the IRS. Grantvello does not know whether a foundation is accepting proposals right now: a past grant is not an open opportunity. Always confirm current guidelines with the funder before applying.