First, this chapter develops original criteria – inclusiveness, discursiveness, and effectiveness – in order to map information and communication technologies’ uses in consultative processes that can be used for other cases of citizens’ constitutional reforms. Second, reviewing five constitutional consultations cases (Iceland, Estonia, Latvia, Luxembourg, and the German region North Rhine-Westphalia [NRW]), this chapter explores to what extent the opinions emerging online contribute to enriching the debate around the constitutional reforms and to what extent they were included in the consultative and law-drafting process. Not surprisingly, the inclusion is low and self-selection shows a strong bias. Organized interest groups, younger age groups, formerly engaged citizens dominate the online participatory process, which is, in some cases, compensated by the introduction of mini-publics. In most cases, online deliberation had an impact on the drafting of the process, even if it is more-or-less straightforward, depending on several factors such as the publicization on the debates and participatory instruments, the role of political parties, politicians, or powerful civil society organizations and media supporting these instruments, or the level of preparedness and quality of online proposals.