Rosenshine graduated from
Columbia College in 1959. He joined BBDO in 1965 as a
copywriter and became the BBDO New York creative director in 1975. In 1980, he became president of the New York agency and in 1985, he was named chief executive officer of BBDO Worldwide. In April 1986, He spearheaded what is dubbed as advertising's "Big Bang," a merger that created the
Omnicom Group, the world's largest three-network conglomerate consisting of BBDO (Ranked No. 6) and a merged
Needham Harper Worldwide (No. 16) and
Doyle Dane Bernbach (No. 12). He served as chairman of the Omnicom Group for three years before famously "firing himself" and returning to BBDO as chairman and chief executive officer. During his tenure as chairman of Omnicom, its billings grew nearly 30 percent from $4.9 billion to $6.3 billion by early 1989. Under his leadership, BBDO was selected "Agency of the Year" in 1982, 1984, 1993, 2000, 2001 and 2005 by various industry publications such as
Ad Age and
Adweek. In 1991, he served as president of the jury of the
Cannes Lions International Festival of Creativity. In 2006, Rosenshine announced his retirement from BBDO and retains the title of chairman emeritus. ==Honors and awards==