People around the world are mobilizing for constitutional change. This global phenomenon has been underexplored in comparative constitutional studies. This Article introduces the concept of constitutional mobilization, theorizes about it, and offers an original, empirical case-study. First, it develops a general theoretical framework defined by the following key concepts. Constitutional mobilization is the process by which social actors employ constitutional norms and discourses to advocate for constitutional change. Constitutional opportunity refers to the general political and constitutional environment in which constitutional mobilization operates, and particular political and constitutional processes that provoke constitutional mobilization. Constitutional framing concerns identifying constitutional problems and proposing constitutional solutions, the process of which involves invocation of constitutional language, ideas, norms, or symbols presented in national constitutions, transnational constitutional law, and international law. Constitutional resources take the form of state actors who play the influential role in constitutional change.