Child sexual abuse (CSA) is associated with devastating short- and long-term consequences for the individual victims and their families, with significant costs to society also documented. Post traumatic stress disorder (PTSD) has been found to be one of the most significant clinical consequences of CSA, with symptoms persisting into adulthood, especially if left untreated. Treatment outcome studies have examined the efficacy of individual trauma-focused cognitive behavioural therapy (CBT) treatment models as a means of alleviating these symptoms in children. However, little research exists in testing the efficacy of group treatment programs, or the specific cognitive processes that maintain PTSD symptoms in these children. The current research involved 56 children aged 8 to 12 years and their carers. Each child had experienced substantiated sexual abuse. The diagnostic criteria for PTSD and other psychopathologies associated with CSA were assessed by diagnostic clinical interview (the Anxiety Disorder Interview Schedule). This data were complemented by carer reports of their own functioning and the child’s symptoms as well as the child reports of their own functioning on psychometric measures. Two studies were conducted using these children. In Study 1, maladaptive interpretative biases in children with PTSD were examined, and in Study 2, the efficacies of two CBT group programs were evaluated. In Study 1, seven ambiguous scenarios describing different social, physical and environmental (i.e., events at school or home) situations were presented to children with PTSD (N = 26) and a non-clinical control group (N= 20). The group with PTSD reported greater threat bias and avoidance (event was unlikely to occur again) when compared to the non-clinical control group. These responses occurred in situations of perceived social or physical threat, but not in the home or school.