This article considers teaching and learning as a collaborative enterprise in the workplace. The empirical data have been extracted from a field study among apprentices engaged in electromechanical vocational training and education in a major Danish industrial company. Typically, studies of apprenticeship learning do not view aspects of teaching as decisive parts of workplace learning. In this article, I will pin down the specific character of collaborative teaching and learning in the workplace, and compare this with the features of a teaching situation in school with a teacher transmitting knowledge to the pupils. While instruction at school is organised as part of a specifically planned teaching situation, the instruction in the workplace is a more loosely organised part of the joint activity structure of the daily work tasks. The conclusions reached in the article should be useful for the conceptual understanding of instruction and teaching in workplace learning, as well as for policy makers and professionals responsible for the design of apprenticeships and workplace learning. (Contains 2 notes.)