This chapter provides a comparative analysis of how the regional human rights Courts address the question of advisory opinions, identifying similarities and differences. It considers their nature, the power of the Courts to issue (or reject) them and the relevant procedures. It includes a comparative analysis of the jurisdiction ratione personae and ratione materiae of the Courts vis-à-vis advisory opinions, exploring both the legal framework and the interpretation and implementation in judicial practice of the relevant provisions. Finally, the chapter discusses the legal value of advisory opinions compared to contentious cases and provides an overview of the impact that they have had so far on subsequent case-law, on state practice and on the development of international human rights law.