As education becomes increasingly centralised, it is important to understand why some children and young people (CYP) in the UK have become too distressed to attend school, or who manage to attend school but at a considerable cost to their mental health and wellbeing. Using a case-control, concurrent embedded mixed-method research design, parents of CYP completed a bespoke online questionnaire. This included 948 parents of CYP who are currently (738), or have previously (209), struggled to attend school, 149 parents of age-matched control CYP, and parents of 25 CYP who have never attended school. We use the term School Distress (SD) as we found that for the majority of CYP (94.3%), school attendance was associated with emotional distress, with often harrowing accounts of distress provided by parents. Age of onset of SD was early (mean age 7.9 years), with a mean duration of 4 years. SD was associated with poor school attendance (with a cumulative total of 6,197 school days missed in the preceding 20 school days alone), poor academic attainment, significant anxiety symptomatology, and extreme demand avoidant behaviour. Neurodivergent CYP, and in particular, autistic CYP with complex presentations, such as multiple co-occurring neurodivergent conditions and/or multimodal sensory processing difficulties, were significantly overrepresented amongst CYP with SD. The majority of these CYP also experienced mental health difficulties. However, mental health difficulties in the absence of a neurodivergent profile were relatively rare, accounting for just 6.17% of cases. CYP with SD were also more likely than control CYP to have neurodivergent parents and siblings. Hence, whilst not a story of exclusivity relating solely to autism, SD is a story of complexity; occurring most frequently in CYP with complex neurodevelopmental profiles. Despite clear evidence that SD creates a context that engenders negative educational and mental health outcomes, parental reports revealed a dearth of support for these CYP. Moreover, whilst 97% of the CYP described here had once attended a mainstream school setting, only a minority of parents (35.6%) expressed a desire for their child to be educated in a mainstream school in the future. Similarly, only 24.3% of CYP with historical SD are currently educated in a mainstream classroom, with the majority now home-educated. Finally, the majority of parents of CYP with SD (85.56%) were not confident or no longer believed, school to be a suitable and proper place for their child to be educated.