SOM, an initialism of its original name Skidmore, Owings & Merrill LLP, is a Chicago-based architectural, urban planning, and engineering firm. It was founded in 1936 by Louis Skidmore and Nathaniel Owings. In 1939, they were joined by engineer John O. Merrill. The firm opened its second office, in New York City, in 1937 and has since expanded, with offices in San Francisco, Los Angeles, Washington, D.C., London, Melbourne, Hong Kong, Shanghai, Seattle, and Dubai.

Notable for its role as a pioneer of modernist architecture in America and for its groundbreaking work in skyscraper design and construction, SOM has designed some of the world's most significant architectural and urban projects including several of the tallest buildings in the world: John Hancock Center (1969, second tallest in the world when built), Willis Tower (1973, tallest in the world for almost twenty-five years), One World Trade Center (2014, currently the seventh tallest in the world), and Burj Khalifa (2010, currently the world's tallest building). The firm's notable current work includes the new headquarters for the Walt Disney Company, the global headquarters for Citigroup, Moynihan Train Hall and the expanded Penn Station complex, and the restoration and renovation of the Waldorf Astoria in New York City; airport projects at O'Hare International Airport, Kansas City International Airport, and Kempegowda International Airport; urban master plans for the Charenton-Bercy district in Paris, New Covent Garden in London, Treasure Island in San Francisco, the East Riverfront in Detroit; P.S. 62, the first net-zero-energy school in New York City; and the design of the Moon Village, a concept for the first permanent lunar settlement, developed with the European Space Agency and Massachusetts Institute of Technology.

SOM's multidisciplinary practice works across a range of scales and project types, providing services in architecture, building services/MEP engineering, digital design, graphics, interior design, structural engineering, civil engineering, sustainable design and urban design & planning.

The firm's first influential project was Lever House, completed in 1952 to become the first International Style office building in New York City. Constructed of glass and steel at a time when Park Avenue was lined with masonry buildings, Lever House introduced a modernist aesthetic that embodied the spirit of the times and influenced an entire generation of high-rise construction.

In 1962, architectural historian Reyner Banham wrote that, "It gave architectural expression to an age just as the age was being born ... Lever House was an uncontrollable success, imitated and sometimes understood all over the Americanized world, and one of the sights of New York".

In the 1970s, SOM pioneered a new era of skyscraper design with its work in Chicago, including the John Hancock Center (completed 1970) and Willis Tower (formerly Sears Tower), which became the world's tallest structure upon its completion in 1973 and remained so for more than 20 years. Both towers are the result of collaboration between architect Bruce Graham and engineer Fazlur Rahman Khan. Khan invented a tubular framing system that made it possible to build higher than ever before. This system has been adapted and is still used today for some of the world's most recent tallest buildings, including the 828-meter-tall Burj Khalifa, designed by SOM and completed in 2010.

In the 1960s and 1970s, SOM was an early leader in computer-aided design, developing in-house digital tools that preceded the CAD systems used widely today. This work quickly proved valuable in the generation of structural analysis tools that were embraced by Fazlur Khan and his engineering team, aiding the design of projects such as the John Hancock Center.

The activity of an experimental research group at SOM, known as the Computer Group, exemplifies a particularly productive effort within the firm to incorporate technological research into its practice. Through the 1970s and 1980s, members of the relatively small, dedicated group pushed to integrate the computer's enhanced data-storing and analytical abilities into various phases of the design process. Through these initiatives, SOM was able to identify the potential of the computer to not only expedite necessary calculations but also introduce new ways of representing and sharing information. Just as structural engineering came to be seen early on at SOM as a means of generating rather than simply realizing architectural ideas, with concerted effort, computers gained credence at the firm, and eventually throughout the industry, as a catalyst for architectural innovation.