The pontiff, 80, is a native of Germany whose father was anti-Nazi. Benedict was enrolled in the Hitler Youth as a teenager against his will and then was drafted into the German army in the last months of the war. He wrote in his memoirs that he deserted in the war's last days.
It will be the pope's second visit to a synagogue as pontiff. On his first papal trip abroad in 2005, Benedict visited a synagogue in Cologne, Germany, that had been rebuilt after it was destroyed by the Nazis.
"By this personal and informal visit, which is not part of his official program, His Holiness wishes to express his good will toward the local Jewish community as they prepare for Passover," said Monsignor David Malloy, general secretary of the U.S. Conference of Catholic Bishops. Passover begins at sundown on April 19.
Separately, the pope has scheduled a meeting with Jewish leaders and representatives of other faiths for April 17 in Washington.
Park East Synagogue is a modern Orthodox congregation that was founded in 1888 and is located near the United Nations. Benedict will address the U.N. the morning of April 18.
Schneier, 78, has led the synagogue since 1962, while promoting religious freedom and tolerance worldwide. He founded the Appeal of Conscience Foundation, which promotes interfaith tolerance, and received the 2001 U.S. Presidential Citizens Medal for service to the nation.
The pope has been reaching out to Jews, following in the footsteps of his predecessor, Pope John Paul II, who became the first pope to set foot in a synagogue in 1986, when he visited Rome's main synagogue.
Some tensions arose recently over a Good Friday prayer Benedict revived from the old Latin rite that had historically been used as an excuse for violence and discrimination against Jews. Benedict revised the prayer to address Jewish fears, but some Jewish leaders worried that the changes did not go far enough.
Benedict is visiting the United States for the first time as pontiff from April 15-20, stopping in Washington and New York. He will meet with President Bush at the White House, address the presidents of Roman Catholic colleges and universities and hold Masses at Nationals Park and Yankee Stadium.