Life at ZS

From 2 friends to 13,000 ZSers: Celebrating 40 years of passion and impact

By Kailah Peters

Sept. 15, 2023 | Article | 5-minute read

From 2 friends to 13,000 ZSers: Celebrating 40 years of passion and impact

Before it was a global consulting firm, ZS started with Andy Zoltners and Prabha Sinha, two friends who shared a love for solving complex problems. Andy and Prabha met in 1973 at the University of Massachusetts, where they collaborated on a multiple-choice knapsack algorithm to plan meals for the U.S. military that quickly garnered attention from organizations seeking innovative resource allocation solutions.


Andy and Prabha went on to become professors at Northwestern University, joining forces outside school hours to utilize the world’s first personal computer-aided territory mapping system to design sales force alignment models. Before they knew it, their research turned into a small side business called ZS (Zoltners and Sinha) that eventually grew to become what it is today: a firm with more than 35 offices worldwide and more than 13,000 ZSers who use their passion and expertise to transform global healthcare.

Where passion changes lives

In the early days before ZS, Andy and Prabha spent most of their time knocking on doors and calling friends and associates to pitch their nascent ideas. “At that time, Andy was trying everything, from territory alignment and sales force sizing to zero base budgeting and catalog space planning,” Prabha recalls, laughing at the uncertainty and rejection during that time.


In 1977, Andy got a call from a classmate who was working at a top 10 pharmaceutical company’s internal consulting arm. That meeting resulted in the discovery of a new use for their multiple-choice knapsack algorithm—sizing a sales force. This would become a focal point in the founding of ZS.


The two made a big bet on their ideas. Prabha took a six-month sabbatical from teaching and rented out his house to pursue various ideas, including a venture that ultimately fell through. When Andy called Prabha to share news about a contract with Wrigley, an American multinational chewing gum company, in the early 1980s, the deal was a saving grace for them both.

The big break came at a Pharmaceutical Management Science Association (PMSA) meeting in 1982, where Andy made a presentation that included a live demonstration of their ideas on an Apple computer. Three pharmaceutical companies signed on. One of those three companies invited them to visit prospective affiliates in Europe to pitch their sizing ideas. Remembering this trip, Prabha says, “After multiple successful projects in Europe, the VP of marketing asked Andy a question. I don’t remember what it was, but I’ll always remember Andy’s response. He said, ‘I don’t know.’ The whole notion of being honest with clients was as true then as it is now.”


Authenticity has anchored ZS ever since its founding in 1983. Our clients trust us to be committed to excellence and effectiveness and also to be humble and honest. Above all, we live by the core values that Andy and Prabha created: Treat people right, get it right and do the right thing.


With their next client, Andy and Prabha worked to constantly improve the territory alignment algorithm and processes. As clients asked questions, the duo updated the software to meet clients’ needs, another mentality that still defines ZS today. We pride ourselves on our client-driven, technology-enabled approach and collaborative work with clients to solve business needs in innovative ways.

As their business expanded, Andy and Prabha began hiring new talent to grow ZS and grow with ZS. Though the teams were much smaller than they are today, business grew in similar ways—through word of mouth and quality work.


“One of the key things we learned over the years is that hiring isn’t about cloning ourselves. We look for people who can bring new skills, expertise and perspectives,” Prabha says. This mindset fuels the diverse talent of ZS. Only by prioritizing diversity, equity and inclusion can ZS attract people with the wide range of talents and perspectives necessary to help clients meet their business needs.


“The company was flying,” Prabha recounts. “We were expanding geographically, first to London then to New Jersey and so on. Then we started expanding practice areas and industries. All that growth and customer success brought its own challenges. It required a lot of hard work and creative problem-solving.”

Now, 40 years later, ZS has expanded to global healthcare, technology, travel and transportation, agribusiness and food, high tech and much more. We work with clients to optimize clinical trials, market new products and improve business functions. Above all, we remember that on the other side of our innovations and solutions are real people. People who need access to affordable medicines to live long and healthy lives. People who need the latest and greatest medical technologies to diagnose diseases and determine the best course of treatment. And people who need access to goods and services that promote food security, financial well-being and healthy lifestyles. 


Though a lot has changed, much remains the same. ZS still leads by our core values of treating people right, getting it right and doing the right thing. We continually invest in our culture, hiring diverse minds and connecting through close collaboration and social gatherings. And we still use our passion—like the passion Andy and Prabha had when they founded ZS—to change lives.


Prabha says, “My expectation is that every generation will leave a stronger ZS to the next.”


Before passing away in 2023, Andy said, “I hope for a ZS that takes care of its people, takes care of its customers, innovates and builds expertise.”


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