Concept-individuating reference rules offer a well-known route for the explanation of immunity to error through misidentification in judgments involving first person or de se thought. However, the ‘outright’ version of this account—one that sanctions a one-to-one correspondence between the reference-fixing rule and immunity—cannot do justice to the unassailable ground-relativity of the target phenomenon. In this paper, I outline a version of the reference-rule account that circumvents this problem. I state a reference rule for the de se concept that makes space (...) for different non-reference-fixing ways of thinking or perspectives, yielding different grounds for judgment. The proposal and its ramifications, I argue, shed light on the variety of ways in which this kind of immunity has been proved to be present—and indeed absent—in de se thought. (shrink)