DDB Worldwide Communications Group LLC, known internationally as DDB, is an American marketing communications network. It is owned by Omnicom Group, one of the world's largest advertising holding companies. The international advertising networks Doyle Dane Bernbach and Needham Harper merged their worldwide agency operations to become DDB Needham in 1986. At that same time the owners of Doyle Dane Bernbach, Needham Harper and BBDO merged their shareholdings to form the US listed holding company Omnicom. In 1996, DDB Needham became known as DDB Worldwide.

Bill Bernbach and Ned Doyle worked together at Grey Advertising in New York, where Bernbach was Creative Director. In 1949, they teamed up with Mac Dane, who was running a tiny agency. Together they started Doyle Dane Bernbach in Manhattan. Dane ran the administrative and promotional aspects of the business, Doyle had a client focus, and Bernbach played an integral role in the writing of advertising, leading the creative output of the agency.

The agency's first ads were for Ohrbach's department store exemplifying a new "soft-sell" approach to advertising — with catchy slogans and witty humour contrasting the repetitive and hard-sell style in vogue until then. The new agency was initially successful in winning business for clients with small budgets. Their campaigns for Volkswagen throughout the 1950s and 1960s were said to have revolutionized advertising. Notable campaigns included the 1959 Think Small series of Volkswagen advertisements, which was voted the No. 1 campaign of all time in Advertising Age's 1999 The Century of Advertising. In 1959, the firm created the character Juan Valdez for the National Federation of Coffee Growers of Colombia. In 1960, the agency won the account of Avis, then the number-two auto rental company. The tongue-in-cheek approach, "We Try Harder Because We're Number 2," was a major success (and remains part of the company's slogan today: "We Try Harder"). The DDB "Daisy" campaign is considered to have been a significant factor in Lyndon B. Johnson's defeat of Barry Goldwater in the 1964 United States presidential election and landed Mac Dane on the infamous Nixon's Enemies List. 1972's Little Mikey commercial for Quaker Oats ran continuously in the United States for twelve years.

A branch office was opened in Los Angeles in 1954. In 1961, DDB opened its first international office in West Germany to service Volkswagen. Significant growth came in the mid-1960s after the firm signed Mobil and the available budgets grew materially. Offices in London and other European locations were opened. Bernbach was appointed chairman and chief executive officer in 1968 when the agency was publicly listed; he became chairman of the executive committee in 1976.

The impact of Doyle Dane Bernbach's creativity on advertising around the world, and the history of management crises that led to merger in 1986, are detailed in the book Nobody's Perfect: Bill Bernbach and the Golden Age of Advertising. Written by journalist Doris Willens, who was DDB's Director of Public Relations for 18 years, the book is based on oral histories and interviews with the three founders, the line of the agency's presidents, and key creative and account people. By 1986, four years after Bernbach's death, the agency group had worldwide billings of US$1.67B, 54 offices in 19 countries, and 3,400 employees, but showed profits declining 30% on the prior year.

Needham Harper Worldwide started in Chicago in 1925 as Maurice H. Needham Co. with two clients and billings totalling $270,000. By 1934, it was named Needham, Louis and Brorby, Inc., with billings of US$1 million, had signed the Kraft Foods account and had opened a Hollywood office to service its clients' network radio program production needs.

In 1951, the agency opened a New York office to concentrate on the rapidly expanding television industry. That office merged with Doherty, Clifford, Steers and Shenfield in 1965 and changed its name to Needham, Harper & Steers. The Chicago office grew with accounts such as the Morton Company, Household Finance Corporation, General Mills and Frigidaire. The firm won the Oklahoma gasoline account (later Esso, then ExxonMobil) after research indicated that American drivers wanted both power and play, and copywriter Sandy Sulcer, working with psychologist Ernest Dichter, chose the tiger to symbolize that desire, which led to the campaign Put a Tiger in Your Tank. In 1966, the agency opened a Los Angeles office to handle the Continental Airlines business. An office was opened in Washington D.C. in 1971 initially to service some local McDonald's business. Soon, this agency was winning government and media business and an "Issues and Images" division was opened to service corporate public relations. This business would eventually become Biederman & Company. The agency worked on public service campaigns called Buckle Up for Safety as well as a traffic safety campaign entitled Watch Out For The Other Guy for the Advertising Council.

Keith L. Reinhard came from Chicago to head the worldwide firm in 1982 and, by 1986, there were thirty two offices outside the US; American offices in New York, Chicago, Los Angeles, Washington, Boston, Phoenix, Sacramento, San Diego, Baltimore and Dayton; and diversification in Porter Novelli, Biederman & Company and the international direct-response agency DR Group, Inc.