Externalizing behavior (EB) in preschool has been found to predict maladjustment later in life. Therefore, it is important to identify children most at risk for continuing EB beyond preschool. To date, a number of questionnaires are available for teachers to assist in identifying those children. A frequently overlooked aspect in this screening process is the consideration of different dimensions of EB instead of the use of broadband scales. Therefore, a brief, user-friendly teacher questionnaire was adapted to capture different dimensions of EB (hyperactivity, opposition, and physical aggression). First, the a priori three-factor structure of this questionnaire was assessed in a large sample of preschoolers (N = 3,610). Second, factorial invariance of the questionnaire over child gender and child home language was investigated. Results confirmed the three-factor structure of the questionnaire. Configural, metric, and scalar invariance was found for child gender and child home language, which indicates that teachers assigned the same meaning to the three EB-dimensions across these groups.