What is the epistemic position that a scientist must be in vis-à-vis a proposition, p, to be in a good enough epistemic position to assert that p to a fellow scientist within the scientific process? My aim is to provide an answer to this question and, more generally, to connect the epistemological debates about the epistemic norms of assertion to the debates about the nature of the scientific process. The question is important because science is a collaborative enterprise based on a division of labor. It has even been suggested that such collaboration is a part of the scientific method. However, scientific collaboration depends upon communication between scientists—that is, intra-scientific testimony. After distinguishing some different kinds of intra-scientific testimony (Section 2), I provide a specific proposal for an epistemic norm of assertion that generally governs such testimony (Section 3). I argue that the proposal aligns with the requirements of three scientific virtues—replicability, revisability, and accountability (Section 4). The discussion of replicability considers a prominent debate in the social and cognitive sciences. In conclusion, I consider some of the wider questions raised by characterizing scientific collaboration, division of labor, and more generally, scientific method via intra-scientific testimony (Section 5).