The Appalachian Long Distance Hikers Association or ALDHA-East is a non-profit organization founded in 1983 to support and promote the interests of Appalachian Trail long-distance hikers. It "was the first organization of long-distance hikers in the United States".
The ALDHA authors the annual Appalachian Trail Thru-Hikers' Companion (19th edition: ISBN 978-1889386799), a guide to hiking the Appalachian Trail. It also publishes a quarterly newsletter, The Long-Distance Hiker.
The "Endangered Services Campaign" sponsored by the ALDHA provides backpacker etiquette education and encourages hikers to "act responsibly when they are in trail towns as well as on the trail." One slogan in the campaign is "Just because you live in the woods doesn't mean you can act like an animal." The campaign began in 1990 with the publication of a list of behavioral expectations for hikers staying in hostels.
An annual event is the ALDHA Gathering with hiking- and trail-oriented workshops. It is usually held over Columbus Day weekend and has hundreds of experienced hikers in attendance.