Mixed Martial Arts (MMA) is a popular, yet controversial, martial art which have amassed plenty of practitioners and fans in recent years. MMA-gyms frequently conveys the message that the sport of MMA facilitates sociopsychological development; however, the evidence for this claim is weak. Instead, Blomqvist Mickelsson (2019) have reported that young and novel MMA practitioners may increase in aggression. However, the same practitioners also exhibited increased self-control. This finding is peculiar, as the psychological core of these characteristics are opposite to one another. This would suggest that the increased self-control did not mitigate aggression levels. Thus, a series of moderation analyses were performed with the same MMA practitioners (n = 63) who underwent a 5-month training intervention. The results indicated that initial levels of either trait both predicted and interacted with each other. These results suggest that, despite the parallel increase in both characteristics, high levels in one of aforementioned traits may mitigate the other. Finally, further inquiry revealed that, some items in the Self-Control Scale may draw from different dimensions related, and non-related, to aggression; thus, allowing practitioners to increase in both self-control and aggression simultaneously. These findings may have practical implications. Whereas MMA-training may be harmless when practiced by individuals with high self-control and low aggression, the combination of these traits is not common amongst youths at risk.