Maassen won two of the biggest comedy contests in the Netherlands in 1990, the Groninger Studenten Cabaret Festival(GSCF), and Cameretten. The GSCF jury was not pleased with the quality of the contestants that year, and gave Maassen the first prize, remarking he was the best of the year, but still not very good. In the following years, however, Maassen fame grew steadily, especially amongst students. Maassens style was based on stand-up comedy: Alone on stage, telling jokes and stories to amuse the public, without any musical support (a thing common for most Dutch comedians up to that point). Since 2000, Maassens shows are shown on Dutch national television, making him more and more a household name.
Unfortunately the movie Theo Maassen: Tegen beter weten in is not yet available on HBO Max.
| Writing | Theo Maassen | Writer |
| Directing | Norbert ter Hall | Director |
| Directing | Martijn Bouwman | Director |
| Editing | Wouter Jansen | Editor |
| Camera | Jacob 's-Gravesande | Camera Operator |
| Camera | Jochem Timmerman | Camera Operator |
| Camera | Ivo Palmen | Camera Operator |
| Production | Judith Maassen | Executive Producer |
| Sound | Peter Warnier | Sound mixer |
| Camera | Remko van Leest | Camera Operator |
