The Hardest Hit event aims to raise the profile of cuts to disability benefits, and the Lothians-based Learning Disability Alliance has urged people to show their support.
It will take place at 11am on Saturday at the corner of Princes Street and the Mound.
Speakers include MP Margaret Curran and Pam Duncan from the Independent Living in Scotland project, while a series of banners and placards will be on show.
The charity has urged members to encourage others with learning disabilities to attend through letter or phone, as its research suggests a smaller than average number use technology.
For more information visit www.ldascotland.org.