Stress is a widespread feature of work in teaching. Recent accounts of teacher emotions and cultures of teaching have noted that unsatisfactory social relationships with adults, e.g. colleagues, headteachers, parents and inspectors, elicit hostile emotions from teachers and appear to be a source of stress in teaching. This article examines why this should be the case. Some commentators have used labour process theory to argue that the intensification of work and government policies promoting managerialism in schools are the roots of the problem. This article uses qualitative data from a study of primary teacher stress to examine staff relationships in the primary school. It argues that while intensification of teachers' work is certainly involved in eroding positive staff relationships, it is also the changing trust relations in high modernity that are shaping the social relations of low-trust schooling, and impacting negatively on teachers' physical and emotional well-being and their collegial professional relations.