The Atlanta-based Carter Center said the former U.S. president is visiting Nepal to encourage Nepal's political leaders to continue on the path to peace as they prepare to hold elections later this year.
A statement by the center said Carter's delegation would meet with Nepal's Prime Minister Girija Prasad Koirala, the Election Commission, national political party leaders, and representatives of civil society organizations and marginalized groups.
Security at the Katmandu airport was stepped up for his arrival. He did not speak to reporters.
Carter is scheduled to meet the former Maoist leaders whose rebels gave up their insurgency last year to join the peace process. Maoists joined the Parliament and the government this year.
Elections are scheduled later this year for a special assembly that will choose a new constitution and political system for Nepal.
The Maoists are still listed by the U.S. government as terrorists even though they have laid down their arms and joined the political mainstream.
The U.S. insists the Maoists have to first completely renounce violence and establish credentials as a peaceful entity before they can be removed from the terrorist list.
The former rebels have agreed to allow U.N. arms monitors to resume disarming thousands of fighters confined in camps as part of the peace agreement.
The meeting with the Maoist leaders is expected to be the highlight of Carter's visit as he would be the most prominent American to have met the former guerrillas.
Carter, who served as U.S. president from 1977-81, is scheduled to leave Nepal on Saturday.
The Carter Center, which he and his wife Rosalynn Carter founded in 1982, promotes human rights globally.