In saying that it was up to someone whether or not she acted as she did, we are attributing a distinctive sort of power to her. Understanding such power attributions is of broad importance for contemporary discussions of free will. Yet the ‘is up to…whether’ locution and its cognates have largely escaped close examination. This article aims to elucidate one of its unnoticed features, namely that such power attributions introduce intensional contexts, something that is easily overlooked because the sentences that (...) express these attributions admit of both intensional and extensional readings. I argue that this kind of power attribution should inform discussions of Frankfurt’s counterexample strategy, in that an alternative possibility should not be considered robust unless it’s up to the agent whether or not it’s realized. I argue, as well, that understanding robust alternatives in this way sheds light on the relationship between the Frankfurt literature and the Luck Objection to libertarianism. (shrink)