Rodney M. Marcellus graduated from Boston College Graduate School of Social Work in 1973. From 1958 to 1961, Marcellus attended and graduated from the Faculte des Lettres et de Pedagogie, in Port-au-Prince, Haiti. He presented his thesis at the Faculté des Lettres et de Pedagogie in December, 1963. Marcellus is a licensed attorney having completed his studies at the Faculte de Droit et des Sciences Economiques in Haiti.
In 2002, Marcellus retired from the Massachusetts Department of Social Services having worked there as a Social worker since 1988.

Marcellus has had varied employment in Massachusetts, first with ABCD, Action for Boston Community Development; with Wyeth Laboratories and he National Legal where he worked in their accounting departments. From 1965 to 1970, Marcellus was a professor of History and Geographie in Zaire, Africa. From 1962 and 1965, Marcellus worked as a teacher of Latin, History and Geography in Haiti.