 Together with his colleagues, he established a new classification of Lithuanian language dialects.For his work "Lietuvių dialektologija" ("Lithuanian dialectology") (1966) Zigmas Zinkevičius received a Habilitated Doctor degree, and became a professor two years later.In 1973 Zinkevičius took a new position at Vilnius University as chairman of the Lithuanian language department, and beginning in 1988 served as chairman of the Baltic Philology department.