The range of terms that are associated with school attendance, and in particular school attendance problems, is surprisingly difficult to define and reach consensus upon. This chapter discusses socio-political considerations in relation to the terminology used to describe school attendance problems and indicate where absence from school is considered a problem. There is discussion drawing upon relevant literature about particular terminology, including the categorisation of attendance as authorised or unauthorised. The chapter introduces the relation between conceptions of school refusal and truancy to emotional and behavioural mental health difficulties. It acknowledges the overlap in the ways these key labels in the field are understood and the complex association of different aspects of mental health difficulties with school absence that might be due to distress, defiance or a mix of different individual factors. Given the influence of factors beyond the individual student, such as parent-approved school withdrawal or exclusion due to behavioural concerns, I argue that a whole-school approach should be taken to attendance that can also be considered alongside other inter-related work on behaviour, health and wellbeing, and school climate.