AECOM (formerly AECOM Technology Corporation) is a North American multinational engineering company.

About 87,000 employees work at AECOM, and it is in position 157 on the 2019 Fortune 500 list.[1]​.

The official name of the company between 1990 and 2015 was AECOM Technology Corporation, and currently it is AECOM.[2]​ The company is listed on the New York Stock Exchange (NYSE), being identified as ACM,[3]​ and on the Frankfurt Stock Exchange under the code E6Z.[4]​.

Its numerous projects include the design and construction of airports, Olympic venues, ports, railways, mines, stadiums, markets, convention centers, tunnels, real estate developments, skyscrapers, drainage systems, bridges, government laboratory complexes and laboratories, among others.

AECOM's origins can be traced back to Ashland Oil & Refining Company, based in Kentucky, United States, which in turn emerged from Swiss Drilling Company, founded in Oklahoma in 1910 by J. Fred Miles. Miles gained control of about 200,000 acres and created the Swiss Oil Company in Lexington. In 1924, Miles launched an oil refining operation called Ashland Refining Company, headed by Paul Blazer. While the parent company did not fare well, leading to Miles' ouster, Ashland prospered under Blazer's leadership, and in 1936 he was named CEO of the reorganized company, Ashland Oil & Refining Company. In 1966 Ashland acquired Warren Brothers and became involved in road construction and building materials. The company was able to take advantage of the byproducts of the refinery to produce asphalt. Ashland became one of the nation's leading highway construction firms and laid the foundation for AECOM. Through a series of acquisitions and technological developments, Ashland grew to include chemical, petrochemical, road construction, and building materials companies within its scope, laying the foundation for a management buyout of Ashland Technology in 1985.[5]​.

In the 1970s, Ashland Oil & Refining became Ashland Oil, Inc. Five years later, the company consolidated its construction assets into a construction division and also formed a coal subsidiary, signaling a change in focus at Ashland. Although it generated more than $1 billion a year in sales, Ashland was a small player in the oil industry at a time when the cost of exploration was prohibitively expensive. In 1980, Ashland sold its production assets, and a year later it was reorganized as a modified holding company. A new corporate strategy was implemented as Ashland now focused on refining and marketing, and sought to grow its non-refining businesses. In 1984 Ashland acquired Daniel, Mann, Johnson & Mendenhall (DMJM), a global provider of transportation-related engineering services. Originally focused on military projects, after World War II it had become one of the first integrated engineering and architecture firms in the western United States. The acquisition of DMJM also included its president, Richard G. Newman. In 1985, DMJM became part of a new subsidiary, Ashland Technology Corporation. Two years later, Newman was named the new CEO and president.[6]​.