Sachser, CedricCedricSachser0000-0002-9353-7936Kooij, Lieke H.Lieke H.KooijKeller, JacobJacobKeller0000-0001-6694-5507Eilers, RebekkaRebekkaEilersJensen, Tine K.Tine K.JensenLindauer, Ramón J. L.Ramón J. L.LindauerOrmhaug, Silje M.Silje M.OrmhaugPfeiffer, ElisaElisaPfeifferRosner, RitaRitaRosnerSkar, Ane-Marthe SolheimAne-Marthe SolheimSkarBirkeland, Marianne S.Marianne S.Birkeland2026-04-072026-04-0720252000-80662000-8198https://fis.uni-bamberg.de/handle/uniba/114572Background: Research on bullying and child PTSD has traditionally been conducted separately. This study examines the association between bullying and posttraumatic stress symptoms (PTSS) in three international samples, comparing its impact to other potentially traumatic events (PTEs) and assessing whether bullying predicts PTSS when controlling for other PTEs. Method: We analyzed three large clinical samples of children and adolescents referred for mental health care in Norway (N = 3370, 63.4% female, Mage = 14.0), the Netherlands (N = 952, 68.7% female, Mage = 15.57), and Germany (N = 707, 39.0% female, Mage = 13.25), using the Child and Adolescent Trauma Screen (CATS or CATS-2) to measure bullying, PTEs, and PTSS. Two linear regression models were compared per sample: one with variable regression weights and one with constrained weights. We also evaluated unique R² shares to determine the distinct variance each PTE contributed to PTSS. Results: Bullying was reported by 56.2% (Norway), 53.2% (the Netherlands), and 52.6% (Germany); cyberbullying was reported by 17.0% (Germany). Moderate correlations with PTSS severity were found (r = .17–.37 for bullying; r = .36 for cyberbullying). Clinically elevated PTSS were reported by 57.4%–73.1% of those bullied and 78.3% of cyberbullied youth. Bullying remained a significant predictor of PTSS, explaining 3.8% to 22.9% of variance after controlling for other PTEs, age, and gender. Conclusions: From a socio-emotional developmental perspective, bullying is a significant risk factor for child PTSS. This association was stronger when bullying items included threat-based language. Specifying the nature of bullying is crucial in determining whether it meets trauma criteria.engPTSD symptomsbullyingchildren and adolescentscross international samplespotential traumatic events (PTEs)article10.1080/20008066.2025.2589566