Young people with serious chronic illnesses, such as sickle cell disorder, report high levels of negativeexperiences at school that have adverse effects on their health. Disclosure of sickle cell status appearsto be unrelated to improved experiences, and alternative explanations for variable health experiencesat school are required. This paper draws on a multi-methods study of young people with sickle cell disorder in England in an attempt to make sense of variable experiences unrelated to disease severity or to teacher/peer awareness of sickle cell disorder. School ethos refers to the manner in which schoolbased interactions combine to bring into effect school values, including the attitudes expected of young people, the attitudes expected of teachers, how young people relate to each other, how young people relate to staff, how the school relates to the community, and a holistic concern with the spiritual,moral, cultural and social development of the young person. It is proposed that these interactions and resulting values are a key to understanding the variable health experiences of young people with sickle cell disorder at school.