Group training is an Australian initiative to encourage the employment of apprentices and trainees. Duncan Macdonald, Phillip Toner and Nic Croce examine the structure and function of group training organisations (GTOs) over time and identify the factors that drive GTOs to change their structure and function. The authors find that group training is a critical component of Australia's skill formation system, and GTOs are highly responsive and adaptive, but they warn that increasing commercialisation has the potential to threaten the quality of training.