Iraq will hold a nationwide census in October - its first since 1987.
The census will include the semi-autonomous Kurdish region in the north. It will also include questions on ethnicity and religion.
Questions on religion will not delve into sect, so the census will not provide data on the breakdown between Sunni and Shi'ite Muslims.
It will also seek to include, through outreach by Iraqi embassies, people who have fled the country.
A national curfew will be imposed on census day.
The population of Iraq is believed to be around 28 million.