 Mental training intends to support athletes in mastering challenges in sport. The aim of our study was to investigate the differential and shared effects of psychological skills training and mindfulness training on psychological variables relevant to athletic performance (e.g., handling emotions or attention control). We assumed that each approach has its own strengths (e.g., mindfulness has a differential effect on the acceptance of emotions), but for some goals (e.g., attention control), both training forms are expected to be equally successful (i.e., shared effects).