Democratic school climate, critical reflection, and student participation at school have been linked to the development of civic and political attitudes. The study aims to identify the contribution of these characteristics to the development of civic and political attitudes and their impact on students' participation (civic, political, activist, and lifestyle/online). Questionnaire data were collected in two waves with 1589 students from four European countries (Italy, Sweden, Germany, and the Czech Republic). Structural equation modelling tested the effects of school characteristics on different types of participation, mediated by institutional trust, political efficacy, and political interest. The results highlight the importance of opportunities for active involvement and critical reflection in fostering interest, efficacy, and all forms of participation activities. Democratic school climate was found to positively impact institutional trust and efficacy, but not participation. The findings highlight the need for a school environment that invites critical reflection and gives value to students' participation.