More than 1 million people in Peru earn less than the equivalent of about $450 each year. Courtesy of Michael Rizzo/CGAP hide caption

itoggle caption Courtesy of Michael Rizzo/CGAP

St. Agnes Hospital in Baltimore is one of the 131 hospitals run by Ascension Health. It's a not-for-profit, Catholic health care system that treats many low-income patients. St. Agnes Hospital hide caption

itoggle caption St. Agnes Hospital

A woman cultivates seaweed off the coast of Madagascar to counter overfishing. She's working with Blue Ventures, a business that supports its conservation projects by giving ecotours. Courtesy of Skoll Foundation hide caption

itoggle caption Courtesy of Skoll Foundation

A big crowd turned out for the March of Dimes walkathon in Gainesville, Fla., in early March. But overall, the March of Dimes' March for Babies raised $3.5 million less in 2014 than it did the year before. Elizabeth Hamilton/Gainesville Sun/Landov hide caption

itoggle caption Elizabeth Hamilton/Gainesville Sun/Landov

They're members of the global-minded teens club: (left to right) Toluwanimi Sola-Adeyemi of Lagos, Chloe McGill of Seattle and Emine Arcasoy of Chapel Hill. Courtesy of Tolu Sola-Adeyemi, Chloe McGill and Emine Arcasoy. hide caption

itoggle caption Courtesy of Tolu Sola-Adeyemi, Chloe McGill and Emine Arcasoy.

A man carries old plastic containers in March 2012 through the Kibera slum in Nairobi, Kenya. Kenyans living in poverty often collect plastics that they can turn into cash by taking it to companies that recycle it. Carl de Souza/AFP/Getty Images hide caption

itoggle caption Carl de Souza/AFP/Getty Images

The Manhattan-based headquarters of Charity: Water. Elise Hu/NPR hide caption

itoggle caption Elise Hu/NPR

John Mayer sings to tens of thousands at the 2013 Global Citizen Festival in Central Park. The event is part of an effort to end extreme poverty. Stephen Lovekin/Getty Images hide caption

itoggle caption Stephen Lovekin/Getty Images

Bill Gates, Martha Stewart, LeBron James, Lindsay Lohan, Kermit the Frog and Conan O'Brien all got icily drenched for charity. via YouTube hide caption

itoggle caption via YouTube

Haley Nordeen, 19, is spending the entire summer at the Prodesenh center in San Mateo Milpas Altas, Guatemala. The American University student helped build the center's new library. Carrie Kahn/NPR hide caption

itoggle caption Carrie Kahn/NPR