The Gill Foundation is one of the largest private funders of lesbian, gay, bisexual, and transgender (LGBT) equal rights work in the United States. The foundation's mission is "to secure equal opportunity for all Americans, regardless of sexual orientation and gender expression." 
The Gill Foundation was founded by Tim Gill in 1994, two years after the passage of Amendment 2, a Colorado ballot initiative denying lesbian, gay, and bisexual people equal protection under the law. As of 2013, the foundation had granted more than $261 million to nonprofits sharing its commitment to full equality.
The Gill Foundation is most known for its support of nonprofit organizations across the country working to bring about equality for LGBT people. Beyond its grant making, the foundation also has been recognized for its OutGiving program, through which the foundation seeks to build a larger base of philanthropists giving strategically in support of LGBT equality. In recognition of the OutGiving program, Liberty Hill Foundation honored Tim Gill with its Upton Sinclair Award in 2011 "for his vision, passion and leadership in helping to create and continuing to inspire the modern day LGBTQ donor movement." 
The Gill Foundation invests a significant portion of its funding in its home state of Colorado, supporting nonprofits working to improve the quality of life for all Colorado residents. In 2010, $3.7 million out of $11.8 million in grants were to Colorado organizations. The foundation is particularly well known in Colorado for its Gay & Lesbian Fund for Colorado program. The Gay & Lesbian Fund's $1 million challenge grant in 2005 to the Mile High chapter of American Red Cross was one of the largest single donations in the country for Hurricane Katrina disaster relief.
The foundation announced in late 2011 that it would re-evaluate the future direction of the Gay & Lesbian Fund, although it remains committed to its Colorado programs.
- Courtney Cuff, President & CEO (In September 2013, Tim Sweeney announced that he would step down before the end of 2013.)
- Robin Hubbard, Chief Operations Officer
- Bobby Clark, Vice President, Programs and Communications
- Gautam Raghavan, Vice President, Policy
- "Caroline Preston". Grant Making to Gay Causes Exceeds $750-Million. Retrieved 22 Feb 2012.
- "Shannon Donnelly". Report: Arcus Foundation tops list of donors to gay causes. Retrieved 6 Mar 2012.
- "Board Members". Gill Foundation. Retrieved September 12, 2014.
- "Center for Effective Philanthropy" (PDF). The Gill Foundation: Taking A Strategic Approach To Philanthropy. Retrieved 2007.
- "Allison McGee Johnson". Foundation Management: Getting the Most Out of Giving. Retrieved June 2004.
- "Anastasia Ustinova". Philanthropists ensure gay community's future. 31 March 2008. Retrieved 31 Mar 2008.
- "Karen Auge". Gill Foundation to re-evaluate Gay & Lesbian Fund's grant-giving. Retrieved 14 Oct 2011.
- "Sweeney stepping down as CEO of Gill Foundation". Biz Journals. Retrieved 15 April 2013.
The Advocate Op-ed: Where will activism dollars go next?, Feb. 3, 2014
- Ustinova, Anastasia (2007-03-31). "Philanthropists ensure gay community's future". San Francisco Chronicle. ISSN 1932-8672. Retrieved April 12, 2012.
- Johnson, Dirk (11 December 2007). "Grants for Gay Services Grow and Go Mainstream". The New York Times. ISSN 0362-4331. Retrieved April 12, 2012.