[1][2] Metropolitan Constantine was born in Pittsburgh on July 19, 1936, to Stanley (Stanislav) and Catherine Buggan, a Ukrainian family.
He also studied at Saint Vladimir's Orthodox Theological Seminary in Crestwood, New York and Duquesne University, receiving a doctorate in philosophy from the latter.
His pastoral work comprised St. Vladimir Cathedral in Chicago, Illinois and at St Nicholas Church in Troy, New York.
After the death of Patriarch Mstyslav (Skrypnyk) in 1993 he became the Primate of the UOC in America, and in 1994, of the Ukrainian Autocephalous Orthodox Church in the Diaspora.
From 1995 to 1996, the UOC in America and the Ukrainian Autocephalous Orthodox Church in the Diaspora entered in communion with the Ecumenical Patriarchate of Constantinople, and Metropolitan Constantine received the titular diocese of Irinoupolis.