Just like a phantom, the topic of »gene doping« keeps haunting the debates regarding the future of competitive sports for years. Very often, corresponding fantasies and visions culminate in the imagination of super athletes who are permanently manipulated with regard to their genetic disposition. However, the application scenarios to be expected will be far more unspectacular, but more probable and more obvious at the same time. Very soon, we will have to expect the use of new substances as well as of methods in gene and cell therapy for targeted manipulation of gene activity. Their use promises a highly efficient performance enhancement and will be difficult to prove, if at all. This book provides comprehensive answers to the key questions of the further development: Which scientific results could cater to the needs of potential gene doping? Where are the future gateways in top-level and popular sports? And how can prohibitions and monitoring be used in responding to this? Another question will be which individual behavioural patterns of athletes and which social contexts will play a role with regard to the potential »career« of gene doping.