People have long known the power of the written word and therefore very early on they became aware that they had to find a way to control it. Over the centuries, and even millennia, rulers have tried different mechanisms of control, but authors, publishers, sellers and readers have always managed to find ways to circumvent it. Books for children and young people are especially exposed to censorship because they are intended for the most sensitive part of the population. The reasons why books intended for children and those on the reading lists in schools were targeted by censors are varied, but they can be counted in one of four main categories: erotic and pornographic content, violence and criminal acts, deviance from social ideology and discrimination. Although Western countries today loudly advocate freedom of speech, and libraries are obliged to ensure their users the right to free access to information, school libraries often face pressure to remove certain books from the shelves because they are considered inappropriate or even harmful for children and young people. Censorship in school libraries is reflected in many aspects: procurement policy, removal of books from collections, closed collections, denial of information about books and self-censorship. This paper explores the topic of censorship in school libraries, the most common reasons why works intended for children and young people face censorship and the most common methods of its implementation in school libraries. The paper also provides a brief overview of censorship throughout history and the situation today.