The article investigates the phenomenon of code-switching among bilingual speakers – Polish students studying English Philology who switch to English by inserting English words, phrases and even whole sentences while speaking their mother tongue Polish. The study is based on the questionnaire and aims at determining the various reasons and functions of code-switching (CS), the attitudes and the factors which either facilitate or impede its occurrence. The study demonstrates that code-switching constitutes an indispensable part in the respondents’ daily interactions although their attitudes, functions and factors which determine the incidence of code-switching are miscellaneous and vary considerably.