Informant discrepancies are commonly observed in assessment of children but there is a lack of studies evaluating such discrepancies for oppositional defiant disorder (ODD) dimensions and emotion dysregulation. Additionally, gender differences in relation to this topic have also received little attention. The goal of the current study was to examine how parents and teachers differ in their reports on ODD dimensions and emotion dysregulation. Using repeated measures, the first in preschool and the second at the end of first grade in elementary school, we assessed informant discrepancies looking specifically at two separate dimensions of ODD (irritability/mood related symptoms and defiant behavior/vindictiveness) as well as two aspects of emotion dysregulation (emotion regulation and lability/negativity). Potential gender differences were also assessed. Parents and teachers of 162 5–7-year-old children (43.2% girls and 56.8% boys) completed the Emotion Regulation Checklist and the Disruptive Behavior Rating Scale. The results indicate relatively prominent informant discrepancies overall, especially between parents and teachers (Intraclass correlation coefficient (ICC) = 0.151–0.566), but better agreement was found among preschool and elementary school teachers (ICC = 0.499–0.753). Informant discrepancies were overall more evident for defiant behavior/vindictiveness compared to irritability/mood related symptoms of ODD. When informants assessed emotion regulation and lability/negativity, the inconsistencies were much more evident for emotion regulation. Lastly, boys were reported to have overall more severe symptoms than girls, but informant discrepancies were more evident for girls. These findings provide valuable evidence regarding the importance of considering informant discrepancies when conducting multi-informant assessment on young children.
