Career
After graduating from Philadelphia"s Drexel University, he worked as a transport specialist. Living in Chicago, he became involved with the Lithuanian-American organization Santara-Šviesa, and served as an editor for its periodicals. Mockūnas compiled and edited several books that discussed an array of cultural topics: Žodžiai ir prasmė (Words and Meaning, 1982), A. Škėmos Raštai (The Works of A Škėma, 1985), and Pavargęs herojus (Tired Hero, 1997), which discussed the Lithuanian resistance against the Soviet Union in the aftermath of World World War II, Laisvės horizontai (Horizonts of freedom) 2001 together with Aleksandras Štromas and Tomas Venclova.
He returned to live in Lithuania in 2005.