This study tested the effects of individual and group-level characteristics on performance during a mandatory and challenging physical education course at the United States Military Academy (USMA). We focused on attributes related to mental toughness, and examined both self-report and utilized an other-rating scale that measures mental toughness-related characteristics and is important to USMA generally. We examined course scores for 5,581 first-year students over five academic years, accounted for background physical fitness, and determined how mental toughness attributes at the group and individual-level contributed to overall course score and scores on constituent events (e.g. obstacle course, rope climbing). Self-reported optimism, self-reported resilience, and mental toughness items from a peer rating scale, but not self-reported grit, significantly improved course performance. The average score across class section on optimism or the peer rating scale also positively covaried with course score, over and above the individual-level impact of that attribute. Analyses of individual events demonstrated that “group-level character” was important for some events, whereas individual attributes were most important for others. Findings suggested an emergent group character capable of influencing individual physical performance scores. Being a member of a tough group may have comparable effects to individual mental toughness