Informal workplace trainers help employees learn what they need to know and do in order to get their job done. Little is known about the actions of informal workplace trainers, who may be colleagues or supervisors. This study provides an empirical basis for actions undertaken by informal workplace trainers. A total of 350 Australian enterprises were interviewed by telephone. Actions of informal workplace trainers were measured using a list of thirty-two statements based on prior qualitative research. Three factors were found to describe core role dimensions: support, structure, and performance. Also, three types of informal workplace trainer appeared: some had a passive indifferent role conception, a considerable number had a restricted role conception, and many had a broad, active role conception. Relationships of role dimensions and role conceptions with organizational context variables and characteristics of informal workplace trainers were tested as well. The study proposes several directions for further research.