The term "curriculum" has been used almost exclusively in educational circles to refer to plans for the conduct of learning lessons in school classrooms. This paper argues that the concept can be productively expanded to describe learning processes in workplaces, including those in which learning is not the intentional outcome of an interaction. The article first reviews conventional conceptions of curriculum, and then draws on theories of cognition and learning base in phenomenology, symbolic interactionism and situated learning to identify some of the features of a naturally-occurring curriculum in the workplace: the socio-technical and pragmatic elements of the knowledge used in the work environment, the classification and framing of knowledge-use, and the extent to which participants are expected to use the various forms of knowledge. That is, curriculum is essentially a socially-constructed ordering of the knowledge-use in a social context. These concepts are applied to two settings in which high school interns were supposed to be learning something: a history museum and a veterinary clinic.