This article introduces Speculative Usability. Whereas traditional models of usability rely on the salient features of an object–user relationship focused around the uses for which the object was designed, the goal of Speculative Usability is to notice an object as it interacts with other objects (in addition to but including human users) and to be vulnerable to an object’s unintended effects. The payoff of this speculative approach is an increased inventional capacity for usability testing.