A savvy founder knows that developing a positive company culture is top on the list of priorities. It's not so difficult in startup phase, but creating a culture that will grow with you takes foresight and diligence.

This is a mind-boggling phase for new entrepreneurs since most haven't done it before. As their companies grow, founders often struggle to maintain consistent growth without losing their core values and founding beliefs.

These mid-size agencies have felt the growing pains, yet found effective ways to develop and nurture their culture successfully. Remember, your employees are your number one asset; hire well and treat them with respect. This is half the battle.

George Popstefanov, Founder and President, independent digital media agency PMG

We never took it for granted, but when we were fewer than 50 employees, maintaining our beliefs and culture came easily. Once we crossed that mark, though, we began to focus on it. We examined cornerstones of our culture that we needed to protect and nurture in order to continue thriving. We also identified threats as our growth continued, such as more structure and process--both necessary to be sure, but only at "just enough" levels to avoid suffocating creativity and agility.

One of the best things we did was shifting a senior leader from client strategy to focusing on people and culture. Most agencies' senior executives focus only on clients or new business. We chose to be different, and it's why PMG scored 23% higher than our peer set in a recent industry workplace survey, despite growing headcount by 35%.

Agile, accountable, authentic, bold, and diverse -- we adhere to those values through an employee-led steering committee, fully transparent all-company meetings, in-depth manager training and employee engagement surveys, and a broad range of company-sponsored clubs and activities relevant to our team members' interests. We'll surely do more, to stay grounded as we grow.

Jim Nash, Managing Partner, marketing communications agency, Marcus Thomas

Our business has grown significantly over the years and we consistently revisit our core values, which allows us to maintain our culture throughout our company's evolution, including acquisitions we made along the way. Some of our values, including our learning culture, entrepreneurial spirit, and overall respect for ideas and people have manifested themselves in new ways as we've grown. For example, we encourage employees to seek out new learning opportunities including experimenting with the latest innovations or technologies or attending industry conferences and then share their findings with the greater team. Learning and entrepreneurship are part of our DNA and we facilitate an entrepreneurial culture that is education-up rather than top-down, and this challenges people to bring fresh perspectives to the table. On the respect front, we believe that respect is critical for allowing oxygen into organizations and giving people the freedom to explore, learn and grow. Values are truly the touch points that keep a company's culture alive, and for us, constantly revisiting them and applying them in new ways has played a key role in our growth over the last ten years.

Ian Clazie, Co-Founder & CCO, marketing agency, Ready State

When we founded Ready State in 2013, one of our advisors told us a business partnership is like a marriage. All the rules around communication, transparency, respect, and empathy apply. Get it wrong, you poison the relationship and therefore the company. Get it right, business and culture will thrive. We took this to heart and made sure we did whatever we needed to do to keep our three-person relationship strong and built on a solid foundation. That continues today.

We put a lot of emphasis on hiring people we believe are aligned with our company values. We set out to be a different kind of agency, and that's what we've become. Being in San Francisco and Silicon Valley, it's possible for us to feel like a startup but without the bro culture. That's not a common vibe for an agency in my experience. It's scrappy, lean, resourceful, and independent. Building the team well is key because in leadership you can't force culture onto people. You have to give it room to breathe and happen on its own.

We've grown from our original three to around 40 and have our sights set on bigger targets, which will take a larger team. Culture will remain very important and even more impractical to micromanage, so the approach needs to be to create the right conditions, hire good people, share values, and work hard together toward ambitious goals.

Drew Ungvarsky, CEO & Executive Creative Director, digital agency, Grow

Growth and culture aren't mutually exclusive, but if you expand without consistently focusing on your founding beliefs, you'll look up and find your culture is gone.

In spite of our company's name, we've chosen purposeful and relatively slow growth to maintain the high bar for our product. We turn down more work than we take on, but we get to focus on projects and clients we love, without building B and C teams, or phoning in our efforts.

Our clients recognize and respect that as much as our team does. I once heard from a client who managed a large team of marketers: "The only complaint I've ever heard about you guys is that there aren't ten times more of you so we could bring you that many more projects." But she went on to say: "Don't do it. Staying small and focused is what's made you great."

We're now at just under forty full-time staff, bringing on a handful of people each year. I couldn't have told you we'd be this big when we were five, ten or even 20 people, but we've always grown within arm's reach, so it's always felt like an evolution of the same company.

Justin Tobin, Founder and President of innovation consultancy, DDG

The way I structured DDG, as a collective of independent, entrepreneurial professionals, lends itself to a natural growth of the culture as the business itself scales. Much the same way that any type of collective works, whether it's a consulting collective or a food co-op, everyone is responsible for contributing to the business and in turn the culture. That's a built-in advantage of our operational model.

But this same principle applies to corporate environments as well, and that's something we're helping our clients implement in their own organizations. No matter what the structure, the most effective teams typically cultivate a collective culture--despite any corporate hierarchy imposed. A flat or egalitarian culture attracts people that are high skill and high will--people who aren't just assigned work but raise their hand for it, are invested in it, understand it, and are passionate about it.

We encourage clients to imitate the best of startup culture, a culture of collectivity, minus the bad behaviors. In turn, we practice what we preach.