Fast-growing Pakistan is the sixth most populous country in the world, with an estimated 200 million people, but has not held a census since 1998, despite a constitutional requirement for one every decade.
The process starts Wednesday and will deploy a team of more than 300,000 people and involve 55 million forms -- a challenge in a country known for corruption and dysfunction.
It will be the basis for revising political boundaries, parliamentary seat allocations and federal funding, while also giving a clearer picture about religious minority numbers in the Muslim-majority country as well as counting the transsexual population for the first time.
The census is a highly charged issue, coming one year before national parliamentary elections.
"Pakistan is not a country with a homogenous population," said Muddassir Rizvi, head of programmes at the Free and Fair Elections Network, "we are multiple ethnicities, more than 80 different languages are spoken. The count actually determines the political power of various ethnicities."
The mighty Punjab province, for example, could see its political grip weaken as a result of its population not rising at a similar rate to other provinces.
"It is not a well received exercise by political actors. It's only on the orders and insistence of the Supreme Court that this exercise is being undertaken," said Rizvi.
