Tony Ingraffea inspired us. In me, he reinforced the love of programming and amazement at the ability of applied mathematics to represent the real world. At some level, we all want people to recognize and appreciate what we are doing. If you are developing fundamental engineering concepts, you write papers and pursue research. If you are writing software, you want people to use and apply your programs. Thunderhead Engineering grew out of that desire. As a result of research we were doing at Kansas State, Brian Hardeman and I decided that we wanted to commercialize some of our work. In 1998, we were fortunate to obtain a Small Business Innovative Research that supported development of our first product, PetraSim, a user interface for the TOUGH2 code from Lawrence Berkeley National Laboratory. TOUGH2 solves the problem of multi-phase flow in porous media. The development we did for PetraSim has made it possible for us to develop two more products, PyroSim -- that model fires in buildings, and Pathfinder -- that models emergency evacuation. At this time we are completely self-sustaining from software sales and have six fulltime employees. I will discuss how a company can be a long-term approach to ensuring that the work you start will be continued and some of the challenges we face as we look to the future.