There is evidence from the literature that the negative emotions and behaviours that bystanders expressed in reactions to witnessing bullying could have stemmed from self-debasing cognitive distortions and errors in thinking patterns which included personalisation, catastrophising, over-generalisation and selective abstraction. For this reason, the purpose of this qualitative descriptive-exploratory study was to explore and describe 10 early adolescent bystanders' experiences of school bullying following a self-debasing cognitive distortion restructuring intervention. Appraisal and cognitive theory were adopted as the overarching theoretical framework. This is because both theories demonstrated how individual thinking patterns could play a primary and significant role in the development and maintenance of emotional and behavioural responses to events witnessed or experienced. A descriptive-exploratory research design was used because it best suited the purpose of the study. The philosophical assumption underpinning this study emanated from an interpretivism paradigm which is a paradigm concerned with understanding the world from the perspective of people‟s experiences thereof. Purposive sampling was used to select 10 participants who were within the age range of 11 to 13 years for the study. Individual interviews were used as formal data collection strategies while a reflective research journal and audio recordings were used as additional data collection methods. The inductive thematic data analysis process was followed to analyse all data collected. The data was collected and analysed in two stages. The findings of this study, from the pre-intervention phase, indicated that personalisation evoked self-blame and feelings of guilt; catastrophising amplified anxiety and fear; overgeneralisation induced and exacerbated a negative perception of school safety and selective abstraction led to indirect co-victimisation. The findings that emerged at the first stage informed the common concepts that were addressed in the intervention. The findings of this study from the post-intervention phase revealed specifically that the self-debasing cognitive distortion restructuring intervention modified bystanders‟ experiences of school bullying. There were observable reduction in bystanders‟ negative emotional and behavioural reactions to witnessing bullying as a result of learning to challenge the validity and reality of distortions in their thinking patterns. Therefore, it is recommended that school counsellors and educational psychologists should provide adequate support to victims of bullying by equipping them with cognitive restructuring skills to root out the source of bias in their thought patterns. / Thesis (PhD)--University of Pretoria, 2020. / Educational Psychology / PhD / Unrestricted