MacArthur Foundation

The John D. and Catherine T. MacArthur Foundation is an American private foundation that makes grants and impact investments to support non-profit organizations in approximately 117 countries around the world. As of 2025, the MacArthur Foundation has an endowment of $9 billion and provides hundreds of millions of dollars annually in grants and impact investments. Based in Chicago, Illinois, it is one of the 20 largest private foundations in the United States. The foundation has awarded billions of dollars in grants since its first round of giving in 1978.

The foundation's stated purpose is to support "creative people, effective institutions, and influential networks building a more just, verdant, and peaceful world". MacArthur's grant-making priorities include mitigating climate change, reducing jail populations, decreasing nuclear threats, supporting nonprofit journalism, and funding local needs in its hometown of Chicago. According to the OECD, the foundation's financing for 2019 development increased by 27% to US$109 million. The MacArthur Fellows Program, commonly referred to as the "genius" award, annually gives $800,000 no-strings-attached grants to around two dozen creative individuals in diverse fields "who have shown extraordinary originality and dedication in their creative pursuits". The foundation's 100&Change competition awards a $100 million grant every three years to a single proposal.