A popular account of luck, with a firm basis in common sense, holds that a necessary condition for an event to be lucky, is that it was suitably improbable. It has recently been proposed that this improbability condition is best understood in epistemic terms. Two different versions of this proposal have been advanced. According to my own proposal :361–377, 2010), whether an event is lucky for some agent depends on whether the agent was in a position to know that the event would occur. And according to Stoutenburg :319–334, 2015, Synthese, 1–15, 2018), whether an event is lucky for an agent depends on whether the event was guaranteed or certain to occur in light of the agent’s evidence. In this paper, I argue that we should prefer the account in terms of knowledge over that in terms of evidential certainty.