Same-except is a fundamental, domain-general cognitive relation in which entities in proximity to one another are judged to be the Same, Except for some part or property where they differ. This relation can be attested in nonlinguistic modalities such as vision, audition, and taste, and it plays an important role in nonlinguistic categorization. We show that this relation is expressed linguistically by means of a wide range of devices, including (a) lexical expressions such as same and except, (b) contrastive stress, (c) anaphora (e.g. definite and indefinite NP anaphora and VP anaphora), (d) ellipsis (e.g. bare argument ellipsis, sluicing, gapping, and VP ellipsis), and (e) fixed expressions such as vice versa and that goes for. Our approach thereby unifies the semantics of all of these phenomena under a common account that is based on a domain-general cognitive principle. We compare our approach with accounts of ellipsis based on syntactic copying or deletion, showing that although both approaches have their difficulties, the challenges to the copying/deletion approach are more severe.