Some worry that semantic externalism is incompatible with knowing by introspection what content your thoughts have. In this paper, I examine one primary argument for this incompatibilist worry, the slow-switch argument. Following Goldberg (Pac Philos Quart 87:301–314, 2006), I construe the argument as attacking the conjunction of externalism and “skeptic immune” knowledge of content, where such knowledge would persist in a skeptical context. Goldberg, following Burge (J Philos 85(1):649–663, 1988), attempts to reclaim such knowledge for the externalist; however, I contend that all Burge-style accounts (at best) vindicate that a subject can introspectively know that she is thinking that “water is wet.” They do not yet show how a subject can introspectively know what she is thinking—which is the distinctive type of knowing at issue in the slow-switch argument. Nonetheless, I subsequently amend the Burge-style view to illustrate how an externalist can introspectively “know-what” content her thought has, and know it in a skeptic immune manner, despite what the slow-switch argument may suggest. For one, I emphasize that “knowing what” can be ontologically non-committal (so that knowing your thought is about water does not require knowing that water exists). For another, following Boer and Lycan (Knowing who, 1986), I stress that “knowing what” is purpose-relative–and for at least some purposes, it seems possible for the externalist to “know what” content her thought has, even if skeptical hypotheses about XYZ are relevant.