Over the past decade, Western European countries have experienced a surge in Islamist and right-wing terrorism. The terrorist attacks have made the European community aware of the scale of the terrorist threat. The increase in the number of terrorist attacks is due, among other things, to the increasing radicalization, which in effect, in many cases, leads to terrorist activity. Confirmation of the negative effects of increasing radicalization in Western European countries, was a surprisingly large number of young people (men and women) who joined the so-called Islamic State in Syria and Iraq. Therefore, individual countries are implementing their strategies to combat radicalism and extremism, and taking measures aimed at deradicalization of already radicalized people. The main purpose of the article is to analyze the measures taken to counter radicalization and an attempt to assess their effectiveness, based on the example of selected Western European countries.