 If in fact Leo’s causing his decision constitutes his exercising free will, then the difference between his causing a decision to tell the truth and his causing a decision to lie is not just a matter of luck; it is a matter of how Leo exercises his free will. But what can be said to support the claim that an agent’s causing a decision is his exercising free will? Many hold that when an agent exercises free will, it is up to the agent herself whether she does one thing or another. A plurality of alternatives is open to the person, and the person herself determines which alternative she pursues. It is also said that when an agent exercises free will, she is an ultimate source or origin of her action. An agent-causal account may be said to nicely realize these conceptions of free will. On the assumption that incompatibilism is correct, the account’s requirement of indeterminism is needed to secure the openness of alternatives. And its requirement of agent causation may be thought to secure the agent’s determining, herself, which alternative she pursues, as well as her originating her action. (Unlike what we have with any event-causal view, with an agent-causal account, the agent is quite literally an ultimate source or origin of her action.) If the account satisfactorily realizes these conceptions of free will, then it may be credibly claimed that the difference in question between worlds is a matter of Leo’s exercising his free will differently.