Smotrytsky is best known for his "Slavonic Grammar with Correct Syntax" (Грамматіки славєнския правилноє Сvнтаґма, 1619), which codified what is now known as "Modern Church Slavonic" or, more specifically, "Meletian Church Slavonic".
Smotrytsky's work for Slavic grammar can be compared with that of Dionysius Thrax for Greek and that of Aelius Donatus and Priscian for Latin.