While Scott initially got into global issues through a direct service organization working with children in Central America, his interest quickly shifted to policy when he saw a documentary about the link between poverty in Nicaragua and structural adjustment. Since than, he's been pretty laser focused on using his money to influence policy. Instead of pouring his fortune into innoculating kids or drilling wells, Scott has mainly invested in groups which seek to increase government funding for development and health.
In 2001, Scott co-founded the Center for Global Development with Nancy Birdsall and Fred Bergsten, which has gone on to become the leading policy shop in Washington arguing for greater U.S. development assistance and reforming trade policies that hurt the global poor. The Center's growth has been pretty astonishing. It's budget grew to nearly $10 million within ten years, with Scott remaining actively involved as board chair and, presumably, continuing to put up serious money. The details of his giving to the Center are hard to nail down, since Scott doesn't seem to have a foundation and the Center, like most nonprofits, doesn't disclose how much specific funders contribute.
What counts most is Scott's leadership in getting the Center for Global Development set up, because a number of major foundations soon followed him in backing the organization. In 2003, a bevy of heavy hitters got behind the Center in a big way: Gates, MacArthur, Rockefeller, OSI, and Hewlett. And the big money has been flowing ever since. Gates has given over $35 million; Hewlett has done at least $20 million.