Pasadena kid. San Francisco builder. The college student who walked into Dinwiddie Construction in the mid-1970s and walked out, two decades later, owning the place.
On April 1, 2025, Greg Cosko did the one thing CEOs rarely do gracefully. He left the corner office. After nearly thirty years running Hathaway Dinwiddie Construction Company, he handed the title to Kevin O'Riordan and slid one chair over. Executive Chairman. Same building, different verb.
The chair shift is the news. The career is the story. Cosko has been at Hathaway Dinwiddie - or its predecessor, Dinwiddie Construction - since he was a San Francisco State student in the mid-1970s. That is not a tenure. That is a geological layer.
In 1990 he was promoted to Senior Vice President and put in charge of the Los Angeles office. A few years later he was appointed Executive in Charge of the Getty Center, one of the largest private construction projects in California history. The Getty took until 1997. By the time it opened to the public, Cosko had already been promoted to President and CEO of the company - a year earlier, mid-build.
That same year, 1996, he led a management buyout of Dinwiddie Construction and stitched it together with Hathaway in a simultaneous merger. Two of California's oldest construction firms became one. Headquarters stayed in San Francisco. That last sentence is short on purpose. It was a fight worth having.
Most CEOs trade nameplates every five years. Cosko's resume is a single column.
Not all under Cosko, but all under the same shingle. The Hathaway Dinwiddie portfolio is a tour of California's skyline.
Cosko's signature build. One of the largest private construction projects in California history.
The pointy one. Defines a skyline. Built by the firm Cosko later ran.
Where the SF Symphony plays. An acoustically demanding job for a contractor's contractor.
UC Irvine School of Medicine. Healthcare construction with quiet precision.
"Hathaway Dinwiddie has a culture of fostering opportunity... we will remain California's choice for certainty of delivery and outstanding value." Greg Cosko, on the 2025 leadership transition
Construction is a confidence business. Owners hand a general contractor a number with eight digits and a date eighteen months out. The contractor either hits both or doesn't. Reputations compound. Mistakes compound faster. Cosko's firm doesn't market with adjectives. It markets with addresses. The Getty. The Pyramid. Davies Hall. Corporate campuses no one tweets about because they were finished on time.
What's unusual about Cosko isn't ambition. It's the absence of pivot. He never went into developer life. Never tried venture. Never started a side firm. He took one job at one company, worked his way to the top, then bought the company. The buyout is the only plot twist in an otherwise straight line - and even that wasn't a power play. It was a quieter thing: keep the headquarters in San Francisco, keep the people, keep the culture, change the cap table.
In the construction world, that is itself a position. While larger national firms swallowed regional builders through the 1990s and 2000s, Hathaway Dinwiddie stayed California-shaped. Three offices: San Francisco, Santa Clara, Los Angeles. A 510-person workforce. Roughly $300 million in annual revenue. The company is the kind of size that gets noticed by clients and ignored by analysts. Cosko seems to like it that way.
His public face is light. There are a handful of YouTube videos - a Take Five interview titled "Why Hathaway Dinwiddie," a company culture clip, an Allen Matkins panel from a San Francisco construction summit. He shows up. He talks about delivery and people. He does not perform.
The boards tell another story. Past chair of the San Francisco Chamber of Commerce. Board member of the San Francisco State University Foundation, the place that hired him in the mid-1970s and apparently never quite let go. Past chair (2021-2022) of the Construction Industry Round Table, the trade body of roughly 120 CEOs from the largest US design and construction firms. That last one matters because it's elected by peers. The Round Table is where general contractors compare scars.
He keeps showing up for civic boards. Serra High School Board of Regents. The Chamber emeritus seat. There is a pattern - if an institution mattered to him personally or to his city, he gives it a board seat's worth of attention. That's not philanthropy as ribbon-cutting; it's the same loyalty operating system that kept him at one firm for half a century.
The Getty Center, finished in 1997, isn't really one project. It is six interlocking buildings on a hilltop in Brentwood, served by a private tram, faced with imported travertine, with mechanical systems for art conservation and a deadline that famously slipped a decade in design. Cosko didn't design it. He was the executive in charge of building it. That role is part air-traffic-controller, part diplomat, part insomniac. It is also where construction CEOs are forged.
By the time the museum's doors opened, he was already running the company. He has been running it ever since.
A rough decomposition of Greg Cosko's working life inside one firm. Approximate, illustrative, and probably a year or two off.
He is from Pasadena. He built the Getty Center in Los Angeles. Then he ran a company headquartered in San Francisco. A California career, geographically thorough.
The 1996 buyout and the merger that formed Hathaway Dinwiddie happened in the same year he was promoted to CEO. That is a lot of paperwork for one calendar.
He has been on the San Francisco State University Foundation board - and SF State is where his career began. The loop closed.
Married to Deborah, three sons, lives in Hillsborough. Not glamorous. Not meant to be.
He chaired CIRT in 2021-22. Roughly 120 of the country's biggest design and construction CEOs vote on that. It is not a participation trophy.
His successor as CEO, Kevin O'Riordan, took the title on April 1, 2025. April Fool's Day was the actual handoff date. Construction people enjoy this kind of timing.
Greg Cosko is not a poster. He is a builder. The internet on him is concise.