The aim of this study was to investigate the relationship between callous-unemotional (CU) traits and response to rewards and discipline in adolescent boys using a mixed-methods approach. Participants comprised 39 boys aged between 12 and 13 years and 8 teachers. Quantitative findings showed that CU traits were significantly related to punishment insensitivity, controlling for conduct problems, autism symptoms and hyperactivity. In contrast, there was no significant association between CU traits and reward sensitivity. Qualitative analysis indicated that teachers view children high in CU traits as responsive to fewer reward and discipline strategies, and strategies need to be implemented and monitored with care to avoid unintended, undesirable outcomes. However, time out, praise, support from other staff and maintaining a positive teacher-child relationship were identified as effective strategies. Findings emphasise the need to carefully select, modify and implement existing evidence-based classroom behaviour-management strategies with high-CU children.