Background Childhood adversity can include traumatic experiences and exposure to other risk factors; consistently predicting poorer psychosocial outcomes in adulthood. Relatively little research has investigated the impact of cumulative risk exposure in childhood. Using data collected in a specialist clinical setting, we investigated the associations between risk exposure, psychopathology and psychosocial functioning. Method Participants were children attending the Attachment and Trauma service at Great Ormond Street Hospital in London ( N = 132, M = 10.25, SD = 3.35). Data was collected via routine clinical practice during multi-disciplinary assessments. Data was collected on developmental and trauma history, psychopathology, and functioning (CGAS), using standardised measures, clinical interviews, and observations. Results All children had experienced at least one risk factor, with 78% reporting multiple exposures, including witnessing interpersonal violence (52%), neglect (48%), and physical abuse (42%). Other risk exposures included exposure to alcohol (17%) and substances (24%) in-utero, as well as social risk factors such as multiple foster placements in some cases. In this sample, 65% of children met criteria for at least one psychiatric diagnosis (Anxiety = 31%, PTSD = 28%, Depression = 8%). High levels of functional impairment were found, with 52% of children falling into the highest categories of ‘obvious’ or ‘severe’ problems. Multiple risk exposure significantly predicted PTSD (OR 9.64 (1.1, 83.7)), but did not predict anxiety, depression, or functional impairment. Conclusion This study highlights the rates of cumulative risk exposure in this clinical sample. The findings demonstrate the importance of detailed and accurate clinical assessments in ascertaining trauma histories in children with known histories of adversity and maltreatment. There are implications for assessment and treatment, such as the importance of clear guidelines on treating PTSD in children with complex trauma histories.