While the efforts of teachers are crucial for preventing and stopping degrading treatment, harassment, and bullying in schools, research has found that teachers' understandings of such terms may vary significantly. In this qualitative study, we take a social-ecological perspective to investigate Swedish schoolteachers' understandings of the terms degrading treatment, harassment, and bullying. The study is based on ethnographic research, which included participant observations and interviews conducted at three schools. The findings demonstrate not only the ways in which teachers blurred the conceptual boundaries between degrading treatment, harassment, and bullying, but also how such blurring was influenced by factors within the microsystem, mesosystem, exosystem, macrosystem, and chronosystem, and how the juridification of degrading treatment and harassment encouraged teachers to construct hierarchies of what they perceived to be more or less serious incidents.