Objective: Physical educators' implicit theory of children's deviant behavior in primary education was investigated and compared with diagnostic criteria. Method: A total of 60 physical education (PE) teachers reported deviant behaviors during lessons. Experts sorted these behaviors together with the official diagnostic criteria into categories based on perceived similarity in content. Results: Hierarchical cluster analysis on the derived similarity matrix among the behaviors suggested that PE teachers focus more on attention problems, disobedience, and aggressiveness when internalizing behaviors, such as anxiety and low energy, were less reported. Conclusion: PE teachers may be important and useful informants on children's behavior in school settings. (J. of Att. Dis. 2012; XX(X) 1-XX).