This study analyzes the constitutional provisions in 44 predominantly Muslim countries addressing the relationship between religion and the state, freedom of religion or belief, and other related human rights as measured against recognized international human rights standards. The geographic diversity of the Muslim world mirrors a central finding of the study, that predominantly Muslim countries encompass a variety of constitutional arrangements - ranging from Islamic republics with Islam as the official state religion, to secular states with strict separation of religion and state. Key findings of the survey include: More than half of the world's Muslim population (estimated at over 1.3 billion) lives in countries that are neither Islamic republics nor that have declared Islam to be the state religion; countries in which Islam is the declared state religion may provide constitutional guarantees of the right to freedom of religion or belief that compare favorably with international legal standards; countries in which Islam is the declared state religion may also maintain constitutional provisions protecting the related rights to freedom of expression, association, and assembly - or the rights of equality and nondiscrimination with regard to, inter alia, religion and gender - that compare favorably with international standards; and a number of constitutions of predominantly Muslim countries incorporate or otherwise reference international human rights instruments. This study is also available in Arabic.