Tactical understanding, a special case of strategic knowledge, has been shown to be key to success in team sports. This study explored the effectiveness of a question-generation technique to unearth high school rugby players’ mental models of defensive tactics. Further, the sophistication of the resulting mental models was assessed in relation to select domain-general (e.g., number of sports played) and domain-specific (e.g., years of rugby play) variables. Fifty-eight participants responded to three scenarios that involved defensive tactical play and generated questions about cues for each scenario. Data from participants’ questions were used to construct players’ mental models of defensive tactical understanding. Although there was noticeable variability in the resulting mental models, the overall tactical understanding was judged to be tactically simple. Results from multiple regression analyses suggested that both domain-general and domain-specific factors predicted the sophistication of players’ mental models. Limitations, directions for future research, and implications for researchers, educators, and coaches are discussed.