ST. LOUIS (September 27, 2006) - The U.S. Department of the Interior's Office of Surface Mining (OSM) has honored one of Arch Coal's (NYSE: ACI) mines for its exemplary interaction, communication and involvement with the surrounding communities.

Black Thunder mine was recently presented with the 2006 National Good Neighbor Award in Washington, D.C. Black Thunder mine was selected from more than a dozen Good Neighbor award winners submitted at the state level.

As one of the world's largest coal mines, Black Thunder was named a Good Neighbor for its strong community involvement, including its quick response to the tornado and aftermath in nearby Wright, Wyo. last year. Black Thunder provided emergency responders, a solution for disposing of 500 truckloads of debris, and free meals to more than 300 homeless residents and disaster relief volunteers.

"It is a well-deserved honor for the employees of Black Thunder to be nationally recognized as good neighbors," said Arch Coal's Chairman and Chief Executive Officer Steven F. Leer. "Being a good corporate citizen is integral to Arch Coal's overall success. I commend the individual and collective efforts performed each and every day by our operating subsidiaries to make a positive difference in the communities in which we live and operate."

The Arch Coal Foundation and Black Thunder employees provide countless volunteer hours and more than $120,000 to educational groups and nonprofits in Wyoming. Black Thunder provides public tours to more than 4,000 visitors annually, and the Arch Coal Teacher Achievement Awards program recognizes 10 Wyoming teachers with $2,500 cash awards each year.

Since the awards program began in 1986, Arch Coal and its subsidiaries have won the coveted Director's Award three times, the Good Neighbor Award twice, the National Award twice, as well as the Special 25th Anniversary Award. For a more complete list of Arch Coal's environmental awards, visit www.archcoal.com/aboutus.

The Department of Interior's Office of Surface Mining (OSM) is the agency responsible for regulating the environmental impacts of coal production. Nominations from coal mine operators are first judged by state mining regulatory agencies, which forward state-level winners to OSM Headquarters for final judging at the national level. A panel of experts from OSM completes the final judging. More information is available at: http://www.osmre.gov/activerules01.htm.

Located in the southern Powder River Basin of Wyoming, Thunder Basin's Black Thunder mine employs roughly 1,000 people and produces more than 8 percent of the U.S. coal supply each year. Earlier this year, Black Thunder earned the statewide Good Neighbor award from the Wyoming Department of Environmental Quality.

Arch Coal is the nation's second largest coal producer. The company's core business is providing U.S. power generators with clean-burning, low-sulfur coal for electric generation. Through its national network of mines, Arch supplies the fuel for approximately 6 percent of the electricity generated in the United States.