The magazine also ranked the company as first in the engineering and construction category.
The list is featured in the magazine’s March issue.
Flour said FORTUNE has been collaborating with Hay Group since 1997 in identifying and ranking the world’s most admired companies and uncovering the business practices that set these companies apart from their peers.
More than 1,400 companies were surveyed, including the 1,000 largest in the U.S.
Several contractors headquartered in Maryland and Virginia also made the list.
Fortune selected Booz Allen Hamilton, CACI International, General Dynamics, Lockheed Martin and Northrop Grumman.