Regional organisations play an increasingly important role in strengthening and upholding the rule of law. Depending on their mandates and regional contexts, this role takes various forms. Regional organisations are also seeking to strengthen constitutional governance in their member states by developing regulatory frameworks that reject and sanction unconstitutional transfers of power and attempts to remain in power unconstitutionally. In some case, they are also mandated to assist in the actual design of national constitutions. This publication presents and discusses the initiatives and actions in the field of rule of law and constitution building by regional organisations. It also highlights their achievements, their limitations and the challenges they face, and puts forward policy recommendations for consideration.