San Antonio Magazine for Alamo Heights, Terrell Hills, Lincoln Heights, Terrell Heights, Northwood and Oak Park

Theory Coffee

Theory Coffee finds success connecting with people through coffee and a smile 

By Bruce X. Forey



What was once an abandoned gas station is now something of a cultural gathering spot in 78209. It started almost a decade ago with a Theory, if you will, that ended up bringing people from different socio-economic backgrounds together for coffee, conversation, and kindness.



“People just want to have someone to greet them in a nice way in the morning and be a part of something; be a part of a conversation,” said Mark Vollmer, owner of Theory Coffee. “I think when you can provide a nice cup of coffee, along with that feeling of acceptance from people of all backgrounds, they want to come back.”



You’ll find Theory at the busy intersection of Loop 410 and Nacogdoches Rd. It serves straight up coffee and related concoctions from a customized 16’ x 8’ trailer. 


It’s been a long road since he first opened his business on Groundhog’s Day, February 2, 2015. Mark’s alarm would sound around 3:30 am for the daily drive to set up and serve that first cup of Joe by 6:00 am. After closing at 2:00 pm, he had to repeat the process and do final paperwork before calling it a day. 



“The long hours and six days a week of hauling and serving was beginning to take a toll,” said Mark. “When I started, I gave myself a five-year plan, and it was time to evaluate. I knew I wanted some sort of permanence.”



Constructing a building on site wasn’t feasible. He explored converting a shipping container, but that didn’t work out. Mark realized all he needed was his coffee trailer, but he just needed to park it permanently. 



Once in place, this solved many problems, but the high-vis location had potential, and he wanted to do more. He revived architectural renderings made for the spot and presented them to the landlord, who gave the go ahead. Mark invested his own financial resources into the upgrade along with a lot of sweat equity. Working through part of the pandemic, construction started in September 2021. Theory held its grand reopening in May 2022. 



“It was kind of like our Pinocchio in that we became a real coffee shop. That was our dream, just to be like a real shop,” said Mark. “Now we can establish roots, dig in a little bit, give it more character, express what we want as a space for customers.”



The result is a model food park with contemporary design features, more seating, landscaping, and space for an additional food trailer. 



With more time available, Mark began exploring other opportunities. He’s now open seven days a week – adding Sundays back in August 2023. He also converted a Honda Micro van for a Theory-branded mobile espresso cart for offsite events. 



Mark and family are now official ‘09ers. They recently purchased a home in Northwood area, just a 10-minute walk from the coffee stand. 



“Living next to the shop has been awesome and really plugs us into the community,” said Mark. “When we shop or grab a bite to eat in the neighborhood, we always run into a handful of customers. It’s been a great experience interacting with them.”



Theory is a unique name for a coffee shop, and so is the way the term came about.



“Every single name we thought of was taken,” Mark said. “My wife was teaching a color theory class and asked what I thought about “theory.” She was surprised I liked it. It has nothing to do with coffee and is opened ended. I mean, coffee theory, but what is that?”



According to Britannica, theory is an idea, or set of ideas, intended to explain facts or events. Whether intended or not, Mark Vollmer put in place a theory, through Theory. A friendly gathering spot can draw people from diverse backgrounds to share in a good cup of coffee and relax for a bit before they go about their day. Theory proven. 


Bruce is a skilled real estate agent serving 78209 and beyond. He enjoys helping client’s market and sell their property, find a dream home or discover investment opportunities. He has advanced training as a luxury homes specialist, with pricing strategies, residential home inspection for real estate agents, and military relocation. Learn more at, social media, or email:

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