Recently there has been a decline in citizens’ participation in elections and party membership — forms of political activity that are institutionalized and deeply rooted in the political system. They are being replaced by such forms as participation in demonstrations, strikes, boycotts and signing petitions, which, with them being institutionalized to a lesser degree, allow citizens to influence political decisions while maintaining their distance from the political system. Trust in political institutions is considered essential for political participation because it creates a positive attitude towards the political system and prevents alienation from politics in its institutionalised forms. However, political mistrust promotes critical perceptions of political elites, which can lead to increased non-institutionalised political participation. At the same time, researchers have noted the influence on political participation not only of individual-level variables, but also of country-level characteristics — the specifics of the political system within which political participation is realised. The purpose of this article is to investigate whether lack of trust is a prerequisite for or a barrier to political participation and how the characteristics of a country’s political regime are related to political participation, using the example of participation in demonstrations. The results of the European Social Survey and V-Dem data analysis demonstrate that participation in public demonstrations is negatively related to trust in political institutions. In addition, two characteristics of the political regime are found to be associated with participation in demonstrations — in countries with greater access to justice and higher levels of physical violence, citizens are more likely to participate in the form of political activity that this article is looking into.