The significance of citizen participation is increasingly being acknowledged in the context of constitutional change. The chapter will focus on deliberation – in particular, in the guise of citizens’ assemblies – in relation to constitutional reforms. Various processes of constitutional amendment and constitution-making – or more broadly relating to issues of quasi-constitutional standing – have included forms of citizen deliberation. Deliberative democratic practices are situated within the bigger picture of citizen participation in constitutional reforms, and the basics of deliberation introduced, to subsequently examine a number of selected cases of citizen deliberation in processes of constitutional change, regarding exponents, forms of participant selection, site of deliberation, types of deliberation, outcomes, and manifestations of participation in the process. The final section discusses a number of critical issues, including the ad hoc nature of deliberative processes, the issue of how to connect micro-level to macro-level deliberation and issues regarding representation, legitimacy, and empowerment.