Racism, xenophobia, hate speech and social exclusion are in a number of cases leading to a general perception about problems with effective democracy. Also, another important issue is the general feeling in a number of European citizens about the existence of an important democratic deficit in EU. Strongly connected with democracy is the issue of trust, especially the trust in democratic institutions and political elites. Last years there is also an important issue of youth mobilization leading to violence which is linked with the general perception about democratic deficit and with the mystification about the negative role of elites and their possible influence in democratic institutions. Furthermore, prevention of extremism and violence policies are strongly connected with the enhancement of democratic citizenship. The aim of this lecture is twofold. From the one side to examine the linkages between social exclusion and youth extremism with political violence and from the other side to present policy proposals about effective prevention of extremism and violence using as an important tool the enhancement of democracy and the active engagement of citizens. Finally, the lecture will highlight the challenges for democracy and democratic participations raised by the polarisation within European societies, especially as an outcome of the migration and security crises.