pt. 1. A synthetic approach pt. 2. Popular participation in constitutional change : theoretical and historical aspects pt. 3. Lessons from long direct-democratic experience : the equilibrium between democracy and constitutionalism in Switzerland and California pt. 4. New trends in popular involvement : best practices and fatal mistakes in the Icelandic and Irish cases pt. 5. The dilemma of introducing constitutional referendums : Luxembourg and Greece pt. 6. EU aspects of popular participation : European integration, national sovereignty and direct-democratic procedures.