This chapter considers the effectiveness of an emerging pathway of institutionalization of the human rights regime: constitutional incorporation. The inclusion of human rights norms in national constitutions has become commonplace. Several quantitative studies have identified this trend as one of several factors associated with improved human rights performance by states. Other studies have called that general conclusion into question, and instead posited that constitutionalization improves human rights outcomes only in limited circumstances. This chapter reviews that literature, with a particular emphasis on constitutionalization of human rights law in the Global South, where much of the cutting-edge scholarship in this area is emerging. Research on the effectiveness of constitutionalized human rights law is crucial to the efforts of those advocates, policy makers and scholars who have a vested interest in seeing that human rights treaties become more than mere words on parchment.