Three former presidents will join President Obama Friday to commemorate the 20th anniversary of AmeriCorps.

President Obama will address AmeriCorps members on the South Lawn of the White House, where he will be joined by President Bill Clinton. Obama's speech will be streamed to ceremonies around the country. AmeriCorps members will be taking a pledge to serve the organization at the ceremonies.

Five presidents at the Bush library in Dallas last year. (Photo by Kevork Djansezian/Getty Images)

President George W. Bush and Laura Bush will also appear in a video that will be shown at more than 80 pledge ceremonies from New Hampshire to Guam. President George H.W. Bush will hold a pledge ceremony at his home in Kennebunkport, Me.

Clinton signed the National Community Service Trust Act, which created AmeriCorps, back in 1993.