Nigeria's President Muhammadu Buhari is meeting his US counterpart, Barack Obama, to discuss the fight against Islamist militant group Boko Haram.
President Obama's wife Michelle got involved in the online campaign, #BringBackOurGirls, after the group kidnapped some 200 girls last year.
The US sent surveillance flights over Nigeria to help locate them.
However, the US refuses to sell weapons to Nigeria because of concerns over its army's human right record.
The two are also expected to discuss the recovery of money stolen by Nigerian officials, which is believed to have been deposited in US bank accounts.
Nigeria is Africa's most populous nation, biggest economy and biggest oil producer.
Mr Buhari, a former military ruler, was invited to Washington shortly after winning election in May - the first time an opposition candidate had won a national election.
- Latest new updates from Africa (http://www.bbc.co.uk/news/live/world-africa-33576653)
Analysis: Nasidi Adamu Yahaya, BBC Africa, AbujaNigeria is seeking US co-operation in combating Boko Haram militants.
The US had previously agreed to help Nigeria fight the insurgency, especially after more than 200 school girls were kidnapped by the militants group from their dormitory in Chibok early last year.
However, relations between the US and the administration of Nigeria's former President, Goodluck Jonathan, soured, amid accusations of human rights violations by the Nigerian military.
President Buhari will also seize the opportunity to seek US assistance to recover billions of dollars from bank accounts in the United States, Switzerland and elsewhere.
The US and other G7 countries had promised to assist Nigeria discover the money - if the country could provide evidence that it had been stolen from the country.
Nigeria will also need US assistance in the fight against corruption, which is one of the issues the country's president had promised to tackle during his campaign days.
Boko Haram at a glance
- Founded in 2002, initially focused on opposing Western-style education - Boko Haram means "Western education is forbidden" in the Hausa language
- Launched military operations in 2009
- Joined Islamic State, now calls itself "West African province"
- Thousands killed, mostly in north-eastern Nigeria, abducted hundreds, including at least 200 schoolgirls
- Seized large area in north-east, where it declared caliphate
- Regional force has retaken most territory this year
Why Boko Haram remains a threat (http://www.bbc.co.uk/news/world-africa-32604782)
Source: BBC