The President of Afghanistan's transitional government, Hamid Karzai, has signed the country's new constitution at a ceremony in Kabul.
Karzai [R] shows the constitution to former king Zahir Shah
The document was agreed earlier this month at a grand assembly, or loya jirga, of regional representatives.
It is intended to pave the way for elections later this year.
However, doubts remain about the chances of holding those polls because of continuing insecurity in large parts of Afghanistan.
Mr Karzai signed the document in a ceremony at the foreign ministry in Kabul in front of ministers, ambassadors and military officers.
It is Afghanistan's first constitution since the collapse of the Taleban regime just over two years ago, but the eighth in its history.
The first was introduced by a king, the sixth by a communist.
This latest constitution is a joint effort, drafted by an Afghan Government commission working with the United Nations and US officials.
It envisages a strong presidency and enshrines equal rights for men and women.
It describes Islam as the country's sacred religion but guarantees protection for other faiths.
But the 12 chapters in 161 articles were actually adopted three weeks ago after long and fractious debate at the constitutional loya jirga.
This delay has led some Afghans to ask if late changes were being made.
Government officials, though, dismissed such rumours, saying they have needed the time to ensure various language versions of the constitution match up.
The signing ceremony took place against a background of continuing security concerns which threaten to undermine the next stage of Afghanistan's transitional process, the registration of millions of voters for elections planned for this summer.