Any contextualist approach to knowledge has to provide a plausible definition of the concept of context and spell out the mechanisms of context changes. Since it is the dynamics of context change that carry the main weight of the contextualist position, not every mechanism will be capable of filling that role. In particular, I argue that one class of mechanisms that is most popularly held to account for context changes, namely those that arise out of shifts of conversational parameters in discourses involving knowledge claims, are not suited to the job because they cannot account for the genuinely epistemic nature of the context shift. A form of epistemic contextualism that defines the context through the structure of our epistemic projects is suggested. Context changes in this account are linked to changes in the background assumptions operative in our epistemic projects and the methods used to carry out our inquiries.