He worked in the diplomatic service of the Holy See from 1959 to 1998; he was given the titles of archbishop and nuncio in 1998 and served as Pro-Nuncio to Kenya, India, Nepal, and the United States between 1976 and 1998.

[2] On 17 January 1976, Cacciavillan was appointed Pro-Nuncio to Kenya and Apostolic Delegate to the Seychelles, as well as Titular Archbishop of Amiternum, by Pope Paul VI.

[4] He received his episcopal consecration on 21 February from Cardinal Jean-Marie Villot, with Archbishop Duraisamy Simon Lourdusamy and Bishop Carlo Fanton serving as co-consecrators, at St. Peter's Basilica.

[2] While nuncio to the United States, Cacciavillan recalled years later, he received a phone call in 1994 from a woman warning of a "media scandal" if Pope John Paul II's 1995 visit to the United States included Newark, New Jersey where Archbishop Theodore McCarrick was the subject of rumors about inappropriate behavior with seminarians.

"[11] On 5 November 1998, Pope John Paul II appointed Cacciavillan to a five-year term as President of the Administration of the Patrimony of the Apostolic See (APAS).

[14] Cacciavillan was one of the cardinal electors who participated in the 2005 papal conclave that elected Pope Benedict XVI.