HLW is a full-service design firm headquartered in New York City, with offices in Madison, New Jersey; Stamford, Connecticut; Los Angeles and San Francisco, California; West Palm Beach, Florida; and London.

During the Great Depression Walker and Voorhees worked on the 1933 Century of Progress International Exposition in Chicago and the 1939 New York World's Fair.

Laboratories geared to defense follow, along with structures at the Brooklyn Navy Yard and facilities necessary for the transport of heavy military equipment.

Projects of note during this period included Argonne National Laboratory (the research center for the U.S. Atomic Energy Commission in Lemont, Illinois) and the Savannah River Plant in Aiken, South Carolina, which was built on a site larger than the entire island of Manhattan.

At the same time, the office continued to design extensive testing and research facilities for both private and government clients within the United States.

International projects allowed the firm to bring their designs outside the United States in the late 1960s and early 1970s, including the Centro Sperimentale Metallurgico, a research center for the development of steel projects was completed on a 125-acre (0.51 km2) site outside Rome and the International Institute Of Tropical Agriculture, a research and housing facility on a 3,000-acre (12 km2) site in Ibadan, Nigeria.

In order to accommodate growth in its overseas practice, the firm created a new division of operations, HLW International, with its first offices in Beirut and then in Athens with projects extending to Lebanon and Saudi Arabia.

HLW won awards from the New York Landmarks Conservancy, the Building Owners and Managers Association, and the Metropolitan Chapter of the Victorian Society in America.

Exactly 100 years after the firm's beginning with a commission to design the first telephone building in New York, a new project for NYNEX Corporation was initiated, as was a training center for The Travelers Insurance Companies in Hartford, Connecticut.

For 20th Century Fox in Los Angeles, HLW created a 50-acre (200,000 m2) campus that housed the first fully digital network broadcast center.