The positive effects of youth civic engagement can be felt both at the individual level (e.g., better emotional regulation, a greater sense of empowerment) and at the community level (e.g., a greater likelihood of participation in civic and political activities). They may also be a protective factor for at-risk youth in the short and long term and a valuable element for positive identity development in general. The purpose of this longitudinal study was to assess the impact of an educational intervention implemented in secondary schools to promote youth civic engagement (N = 508 at Time 1, N = 116 at Time 2). The study is divided into two parts: first, it examines the changes stimulated by the project, and second, it uses a path analysis model to explain the intention to participate. Results show that after participation, hostile and benevolent sexism, classic and modern ethnic prejudice, and social dominance orientation decreased, while trust in institutions increased. In addition, the path analysis showed that policy control, social trust, and civic engagement increased the intention of civic engagement at time T1. Despite some limitations, this study may provide useful guidance for those designing and implementing civic education interventions for young people.