The synod, scheduled for Oct. 7-28, 2012, will cover "The New Evangelization for the Transmission of the Christian Faith."
Archbishop Pierre-Marie Carré, archbishop of Montpellier, France, was named special secretary.
The Pope also appointed Cardinal Angelo Scola, archbishop of Milan, Italy, and Cardinal Jean-Pierre Ricard, archbishop of Bordeaux, France, as members of the Council of Cardinals for the Study of the Organizational and Economic Problems of the Holy See.
He named Cardinal Joachim Meisner, archbishop of Cologne, Germany, as his special envoy to celebrations marking the eighth centenary of the birth of St. Agnes of Bohemia. That event will take place Nov. 12 in Prague, Czech Republic.
As well, the Holy Father accepted the resignation of Archbishop Paulinus Costa of Dhaka, Bangladesh, who turned 75 on Saturday. Coadjutor Archbishop Patrick D'Rozario, 68, succeeds him.
And he appointed Father Piotr Greger, 47, of the clergy of the Diocese of Bielsko-Zywiec, Poland, as an auxiliary bishop of that diocese. He will assist Bishop Tadeusz Rakoczy, 73.
Piotr Greger was born in 1964 and ordained in 1989.
The Diocese of Bielsko-Zywiec has some 681,000 Catholics, served by about 630 priests and 640 religious.