Like many other companies, Coachakademie Schweiz is committed to researching the effectiveness of its work. Evaluating its teaching and training programmes is a key factor for the institute. They are therefore an essential component for the company's continued success. The following paper aims to examine how effective the St. Gallen coaching model is and to provide insight into the factors that contribute to its success for coaching participants. Another important factor that will be discussed is the sustainability of this coaching method from the client's perspective.