The Voluntary Act Requirement (“VAR”) is the fundamental predicate for imposing legal punishment. Punishing solely on the basis of evil thoughts or a villainous character is impermissible. The VAR also embodies the notion that we must not punish someone for conduct over which she lacked sufficient control. But why not punish someone for conduct that was not within her control? One answer is retributivist—it would be unjust to do so because that defendant could not have been morally responsible for, and therefore could not deserve punishment for, what she did. Agent causalism is a contentious view about how criminal defendants voluntarily act according to which the defendants themselves cause their free, morally responsible actions, as opposed to events or states of affairs involving them, their brains, their circumstances, and so forth. This article argues that for retributivist justifications of the VAR to be plausible, agent causalism must be true. Agent causalism might be false, and if it is, then retributivism could not play any role in justifying our fundamental legal precondition for ever imposing any criminal liability upon anyone. This article does not argue that agent causalism is false, however. It elaborates and renders plausible an agent causalist position, and it shows how that position could handle types of cases that notoriously pose challenges to the VAR—cases involving complex unconscious conduct, cases involving crimes of omission, and cases involving habitual conduct.