Possible search terms to use:
nonprofit governance
philanthropy policy
donor ethics
civil society
nonprofit ethics
donor influence
Think tanks
U.S. Based:
Brookings Institution – Public policy, philanthropy, and nonprofit sector analysis. Brookings Research Programs
Urban Institute – Center on Nonprofits and Philanthropy – Research on nonprofit trends, donor behavior, and ethics. This is the most directly relevant to nonprofit organizations. Urban Institute has a dedicated center for nonprofit and philanthropy research.
Rand Corporation - Conducts research that often intersects with nonprofit interests, such as education, health, and social services, and collaborates with nonprofits like the Boys & Girls Clubs, American Institutes for Research. Nonprofit Focus: RAND is itself a nonprofit and conducts research relevant to nonprofit sectors like education, health, and social equity.
Center for Strategic and International Studies (CSIS) - While its primary focus is on strategic and international policy, its work often informs nonprofit advocacy and programming in areas like global health, development, and governance. CSIS includes civil society and NGO-related research, especially in development and humanitarian contexts. CSIS Civil Society Research
International:
OECD (Organisation for Economic Co-operation and Development) – Global nonprofit and civil society data.
Chatham House – International policy and nonprofit sector insights.