John D. MacArthur died 30 years ago, but his friends still gather in Palm Beach County to celebrate his birthday every year on March 6.

It is a tribute to a powerful but down-to-earth man who was once the state's largest property owner and among the nation's wealthiest people. His lasting legacy to Florida, the nation, and the world, is the John D. and Catherine T. MacArthur Foundation, built from the assets of his insurance and real-estate holdings.

Before his death in 1978, Mr. MacArthur told the trustees of his new foundation: "I made the money. Now you figure out how to spend it." Today, the MacArthur Foundation ranks among the largest foundations in the United States. Our assets have grown from $844 million when John MacArthur died to more than $6.8 billion. During that time, we have made more than $4 billion in grants to more than 18,500 creative organizations and individuals around the globe. These investments have helped to improve human rights, conserve biodiversity, reform juvenile justice, strengthen communities, support documentary film and public television and radio, and honor creative men and women through the MacArthur Fellows Program.

The Foundation always has had a special relationship with Florida, where John and Catherine made their home after leaving Chicago in 1958. We have invested about $200''million in the state since 1980, primarily in Palm Beach and Martin counties. Our contribution includes donating land to create the John D. MacArthur Beach State Park and to build Florida Atlantic University's Abacoa campus, and support for cultural organizations and community development activities.

In 2004, we established the John D. and Catherine T. MacArthur Fund at the Community Foundation for Palm Beach and Martin Counties with a $20 million endowment, ensuring that grants addressing community needs are decided locally, rather than at foundation headquarters in Chicago.

To date, the fund has supported more than 20 organizations in areas of special interest to John and Catherine: the arts, the environment, education, and the strength and vitality of South Florida's communities. Among others, grants have been awarded to the South Florida Science Museum, Ballet Florida, Street Beat Inc., Big Brothers/Big Sisters of Martin County, Treasure Coast Environmental Defense Fund and the Broadway Reinvestment Coalition.

The foundation's reach extends well beyond Florida, and our grant-making is as diverse as the 60 nations in which our grantees work. Since our first grant in 1978 to Amnesty International, a common thread of the foundation's work has been support for justice. Developing an international system of justice, strengthening human rights protections in countries in transition abroad and reforming our juvenile justice system at home are the three pillars of MacArthur's commitment to advancing justice.

These initiatives focus directly on issues of justice. But the same values are expressed in all our programs. From conservation in Madagascar to public housing reform in Chicago, from defending young girls in India from forced marriages to reducing police abuse in Nigeria, the Foundation works to enhance personal security, protect the rights of the vulnerable, and promote fairness and opportunity for all.

When the John D. and Catherine T. MacArthur Foundation was created 30 years ago, the world was a different place, and our focus was less global. But today, the Foundation's footprints are worldwide, from the Florida beaches where the MacArthurs walked to resurging urban communities across the U.S. to universities in Nigeria and Russia.

As we commemorate what would have been John D. MacArthur's 111th birthday, the best way to honor him is by continuing to invest in building a more just world.