His composition instructors include Joseph Schwantner, Samuel Adler, Martin Bresnick, Bernard Rands, Christopher Rouse, Roberto Sierra, Jacob Druckman, Poul Ruders, and Steven Stucky.
Mellits received a 2004 Foundation for Contemporary Arts Grants to Artists Award.
[2] Mellits's commissions include pieces for the Orpheus Chamber Orchestra, Bang on a Can All-Stars, Assad Duo, Kronos Quartet, and the Meridian Arts Ensemble.
Mellits is a founding member of Common Sense Composers' Collective, which focuses on new and alternative ways of collaborating with performance ensembles.
As of 2011, Marc Mellits lives in Chicago, Illinois with his wife and two daughters, and teaches composition at the University of Illinois-Chicago.