1. Introduction Over the past decades, there has been increasing interest in the assessment of students’ behavior problems related to Attention-Deficit/Hyperactivity Disorder (ADHD; e.g., inattention) and other externalizing (e.g., conduct problems) and internalizing (e.g., anxiety) problems (e.g., Reinke et al., 2023). Empirical research suggests that the characterization of students’ behavioral problem phenomena requires multiple informants (e.g., teachers, parents, students themselves). In contrast to single-informant reports, this approach is expected to provide sufficient sensitivity and specificity; however, the vast majority of multi-informant assessments of ADHD symptoms and related problems rely on external sources (e.g.; Mulraney et al., 2022; Narad et al., 2015) and retrospective childhood ratings (e.g., Lundervold et al., 2020) leading to substantial underrepresentation of children’s self-perspectives in research. The current study aims to investigate the consistency between self-reports, parent reports, and teacher reports of students’ internalizing and externalizing problems. Further, it will be analyzed if students’ gender and diagnosis of special educational needs (SEN) can explain the specificity (i.e., method bias) in teacher and parent reports. 2. Method The present study uses data from a random Finnish community sample of 1446 students (male= 47.6%) aged 9-11 years. Students’ externalizing problems (i.e., hyperactivity/inattention (H/I), conduct problems (CP)) and internalizing problems (i.e., emotional symptoms (ES), peer problems (PP)) were measured from students', parents’, and teachers' perspectives using the Strengths and Difficulties Questionnaire (Goodman, 1997). The dichotomous classification of SEN status used was based on information obtained from special education teachers in the participating schools about students’ received support in Finland’s three-tiered system. To assess the consistency, we applied a correlated trait-correlated method minus one (CT-C[M-1] model (Eid et al., 2003). 3. Findings & Conclusions The initial CT-C(M–1) model indicate good model fit (χ2WLSMV (1283, N = 1378) = 2054.55, p < .001, CFI = .944, SRMR = .087, RMSEA = .021). Results show in general moderate to low consistency between student and teacher or parent reports. Thus, the method specificity for parent and teacher reports was moderate to high, confirming the importance of using different raters. As expected, gender and the status SEN could predict the specificity in other reports of students’ behavior to some extent, in particular for externalizing problems. Overall, the results highlighted the vital role of multi-informant approaches in the assessment of student's behavior problems.

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