At the university of Münster, Germany we conducted a study of the effect of improvisation theatre in the field cooperating with over ten different improv schools in Germany and Switzerland compared to people who train sports. Our longitudinal study, involving 202 participants, unveils the journey of individuals as they immerse themselves in improv training. While immediate effects post-training were not apparent, a deeper analysis reveals compelling patterns. Participants engaging in improv exhibited significant enhancements in creative self-efficacy and self-esteem over time compared to a control group engaged in sports training. These findings not only highlight the enduring positive effects of improv but also pave the way for innovative educational and therapeutic interventions. This talk will present the results of the study and discuss the difficulties in doing research about improv.