Little research has been conducted on the psychometrics of the very short scale (36 items) of the Children's Behavior Questionnaire, and no one-item temperament scale has been tested for use in applied work. In this study, 237 United States caregivers completed a survey to define their child's behavioral patterns (i.e., Surgency, Negative Affectivity Effortful Control) using both scales. Psychometrics of the 36-item Children's Behavior Questionnaire were examined using classical test theory, principal factor analysis, and item response modeling. Classical test theory analysis demonstrated adequate internal consistency and factor analysis confirmed a three-factor structure. Potential improvements to the measure were identified using item response modeling. A one-item (three response categories) temperament scale was validated against the three temperament factors of the 36-item scale. The temperament response categories correlated with the temperament factors of the 36-item scale, as expected. The one-item temperament scale may be applicable for clinical use.