On Thursday, April 17, Pope Benedict XVI celebrated an open-air Mass at Washington’s Nationals Stadium. More than 40,000 people were in attendance, including six U.S. Ambassadors to the Holy See: (l-r) Corinne Boggs (serving 1997-2001), Raymond Flynn (1993-1997), Thomas Melady (1989-1993), Jim Nicholson (2001-2005), Francis Rooney (2005-2008), Mary Ann Glendon (credentialed February 2008). Ambassadors William Wilson (serving 1981-1984, 1984-1986) and Frank Shakespeare (1986-1989) were absent.

The liturgical celebration reflected the diversity of Catholic heritages and sensibilities representative of the Archdiocese of Washington, where the Mass was held. Music composed in the 40 years since the conclusion of the Second Vatican Council was included, as were ancient Latin texts set to chant. A musical highlight was the appearance of opera star Placido Domingo who sang the opening phrase of "Panis Angelicus."