Co-training can be an excellent experience for students and trainers alike, and can support increased learning. This article considers how co-training can be used in health and social care training classrooms. It explores the theory and practice of training with a colleague, which can appear to be an easy option but may in fact be much harder than training alone. By focusing on the relationship between individual trainers and joint training methodologies, the aim of the article is to share information that is useful to full-time trainers and to clinicians who undertake training as an occasional activity.