In 1971, BBDO International became the holding company of all BBDO offices. Sometime in the early 1980s, it became known as BBDO Worldwide. This was followed in 1986 by Omnicom, the result of a merger between BBDO and DDB Needham. This series has material from these entities as well as offices around the world. It is divided into four sub-series: Worldwide, Omnicom Group, Branches, and Subject files.

The Worldwide subseries includes material from both BBDO International and BBDO Worldwide. The International material focuses on the growth of the agency and the collective offices around the world. The Worldwide material is mainly from network meetings held annually for senior staff across all the offices to gather but also includes client list and developments.

The Omnicom Group subseries mostly relate to the merger but also includes some material from the few years after the merger and other agencies under the Omnicom umbrella.

BBDO, Omnicom, and all other iterations have offices located across the United States and around the world. This subseries includes material from these various branches, dating back to 1930. At the end of the subseries are two folders with written histories of domestic and international offices.

The Subject files subseries contain material related to BBDO offices and agencies around the world as well as international development of BBDO, marketing strategies, and media outlooks for various international markets.