Updated Oct. 4 with the co-chair role Hoskins and Cohen are set to assume next year.

Diane Hoskins and Andy Cohen have been together as co-CEOs of Gensler longer than many married couples, with 18 years at the helm of one of the world's largest architectural firms.

The pair, who had very different first jobs in their careers only to end up sharing a title, aren't married. So, while Hoskins and Cohen have learned a lot about each other since they were initially colleagues in the 1980s — they still don't know everything.

"If we had to order [a meal] for each other, I'm not even sure if we would know what to order," Hoskins said in an interview. Her laugh belies a level of collaboration the pair have cultivated in a firm with 7,000 professionals in 53 locations across the Americas, Europe, Greater China, Asia Pacific and the Middle East.

Starting next year, Cohen and Hoskins are scheduled to continue to work together, but as global co-chairs of the firm. Julia Simet and Jordan Goldstein, co-firm managing principals, are slated to succeed Cohen and Hoskins as co-CEOs and lead the firm’s day-to-day operations effective Jan. 1. The dual-leader structure is a regular practice at Gensler, while at other companies the relatively rare business technique is often short-lived, either by design after a merger or during other transitions.  

The sharing of a job between Cohen and Hoskins, which could soon continue into a third decade, comes as Cohen has worked at Gensler for 43 years. Born and raised in New York City, his first job was working at his father's cheese store on Manhattan's Lower East Side, and it led to a lifelong career lesson in doing what you love.

"I was the first college-educated kid in my family. I knew my passion was going to be architecture and design," Cohen told CoStar News. "But I was boxing eggs beginning at 5 years old."

At a critical juncture in his academic career, Cohen found out his dad had cancer and only a couple of months to live.

"He came to me and said you have a choice to take over the store, like your grandfather and great grandfather or follow your passions," Cohen recalled. "He said. 'The family thinks you should sell the store and follow your passions because if you follow your passions, you will always be fulfilled in life.' And that's been my mantra since. And every day, I love what I do."

Chicago-born Hoskins was always enthralled with the incredible buildings she saw in the third-biggest U.S. city, and that was related to the lifelong interest fueled by her first job.

"It was just in my DNA," she said. "My first job out of school was to work with the company that was building the tallest buildings in the world, Skidmore, Owings & Merrill. So it was imprinted on me really strongly, this idea of stretching and breaking boundaries."

A career in architecture was an easy sell for Hoskins, who was already breaking new ground at a young age.

"It was kind of my story without even thinking about it in a bombastic way because I wanted to be an architect, and I was a girl, and I was Black," she said. "All of that meant breaking a lot of boundaries. I went to MIT, which meant breaking some boundaries if you were me."

She was one of four women at Skidmore in a studio with 50 people, but the first female partner at the firm led it.

"I learned a lot about excellence," Hoskins said. She still goes back to visit the first building she ever worked on — 875 Third Avenue in New York. "You remember your first job, but as an architect, you remember your first building."

It may sound like a complicated process to have two people share the top CEO job, but the way Hoskins and Cohen describe it couldn't be more natural. Sharing responsibility is part of the whole culture at Gensler, they said.

"The shared values become this incredible platform, common ground, 100% agreement. We can go in different directions on interests and synergies that we bring, but it's that foundation of our values and point of view on innovation, growth and people and the firm itself that is non-negotiable for both of us," said Hoskins.

They don't remember exactly when they met, but Hoskins was an intern in Los Angeles in 1986 while doing a two-year MBA at the University of California Los Angeles when Cohen was in that California office.

Both consider Ed Friedrichs, president and CEO of the firm from 1995 until his retirement in 2003, a mentor.

"It was both Ed and Art Gensler, the founder of our firm, who took Diane and me under their wings, and we just grew with the firm," said Cohen, adding there was never going to be one person who could replace either man. "Together, we created this collaborative leadership model we really believe has spurred on the tremendous growth of the firm."

Most areas of the firm, which has 29 practice areas, intentionally have two or three collaborative leaders.

"Everybody has things they are great at and not so great at, but when you put people together with different (strengths), it creates a one plus one equals five scenario," said Cohen. "When we get together, the sparks fly because we are coming from different points of view. When you coalesce together, that's when innovation takes place."

Hoskins points to reorganizing the firm into a collaborative approach in 2000 as a critical turning point. "Of everything we have ever done, that was one of the most important things. We can show you how the firm has grown since then. We weren't even CEOs yet," said Hoskins.

Gensler has grown from an approximately US$300 million business to US$2 billion today. The co-CEOs say the growth comes down to unlocking the collaborative approach that changed from local offices to a focus on areas of expertise.

At the beginning of the pandemic, the relationship proved pivotal. Cohen is based in Los Angeles and Hoskins in Washington D.C., but they stayed in close contact during the health crisis.

"We were on the phone and calls non-stop. We were able to rally together and rally the firm," said Cohen. "We could not have done it as successfully alone. I could not have done it alone."

Today, the pair are working — together, of course — on a book titled "Design for a Radically Changing World," based on their experiences. It's expected to come out in 2024.

"You really want to test a relationship, do a book together," Hoskins said with a laugh.