William Stern

Co-Founder and Principal Strategist

William Stern is the Co-Founder and Principal Strategist of Join The Agency.CO, bringing a history of scaling companies through high-volume, performance-driven marketing.

His marketing journey began in 2004 with the founding of Cardiff, where he developed a high-scale direct mail operation, regularly sending over one million pieces a month to small business owners. Recognizing the shift to the digital front, William strategically moved resources from traditional direct mail and pioneered the company’s transition to digital acquisition.

This strategic pivot became the blueprint for Join The Agency.CO. By aggressively testing and scaling campaigns across Google, Meta (Facebook & Instagram), Reddit, and TikTok, he mastered the art of achieving exceptional Return on Ad Spend (ROAS). His success in generating predictable, high-volume customer growth digitally on these platforms led him to co-found this agency with a clear mission: to leverage this proven expertise to help other businesses dominate their own digital battlespaces.

A recognized serial entrepreneur and thought leader, William’s ventures also include The Fraternity coaching platform. He shares his insights as the creator of the Real Business Growth and Real Traffic Summits and as the host of the “A Stern Talk” podcast.