This paper focuses on the description of three languages according to their permission of pronominal subject exclusion. The languages included in this paper are Croatian, Russian and English. Three of them were taken into consideration due to their diversity concerning this phenomenon. The description is based on several articles and books by some of the first linguists who decided to study this issue (e.g. Perlmutter), but this text also includes some of the new researches that illustrate more varieties of NSLs. The aim of the paper is to merely introduce the notion of NSLs and state characteristics generally associated with them. What is more, it is important to exhibit the evidence that prove South Slavic languages to be different from East Slavic ones. In this paper the differences between Croatian and Russian are mentioned with the purpose of demonstrating that Slavic languages have evolved differently from the common ancestor Proto-Slavic. The third language serves as a complete opposite for it functions on unrelated principles. It is inevitable to conclude that English is a non-NSL; nevertheless, there are occurrences of its speakers omitting pronominal subjects without causing misunderstandings among listeners.