jats:titleAbstract</jats:title> jats:pThe goal of this paper is to analyse the role of convention in interpreting physical theories—and, in particular, how the distinction between the conventional and the non-conventional interacts with judgments of equivalence. We will begin with a discussion of what, if anything, distinguishes those statements of a theory that might be dubbed “conventions”. This will lead us to consider the conventions that are not themselves part of a theory’s content, but are rather applied to the theory in interpreting it. Finally, we will consider the idea that what conventions to adopt might, itself, be regarded as a matter of convention.</jats:p>