In this article, a case is made that affect is central in determining students' experience of learning or not learning mathematics. I show how reversal theory (Apter, 2001), and particularly its taxonomy of motivations and emotions, provides a basis for a thick description of students' experiences of learning in a mathematics classroom. Using data from my own ethnographic study, I show how reversal theory can be used to examine the landscape of disaffection from the point of view of students' subjective experience of mathematics in school. This approach highlights the significance of classroom climate in students' experience of disaffection.