As a so-called bathroom break girl at the advertising agency BBDO in 1985, Susan Credle took over for receptionists when they left their desks. When she learned how to type quickly and accurately, she was promoted to secretary. In the decades since, she has become one of the most accomplished women in the industry, holding top executive positions at some of the most esteemed creative agencies. She has been behind numerous memorable campaigns, including the humanlike M&M’s characters and Allstate’s Mayhem ads.

But even today, there are male leaders in the industry who do not acknowledge her. At industry parties, people assume they should be talking to her husband, who is an architect. She tries not to show her emotions at work because when she does, she said, “I immediately am looked at as the crazy woman.”

“I still to this day, when I feel the blood boiling in me and I just want to let it all out, I cut it by 90 percent because I’m a woman,” she said.

Women now make up almost 50 percent of those working in the advertising industry, including a relatively small number, like Ms. Credle, in top executive positions. Yet when a female employee of the J. Walter Thompson agency filed a lawsuit in March accusing the company’s chief executive of racist and sexist behavior, the accusations brought to the surface what women in the industry had talked about for years: that more than half a century after the “Mad Men” era, gender bias, while often unspoken or acknowledged, continues to affect how they are treated at work, whom they interact with and what positions they hold.