Perhaps the central question in action theory is this: what ingredient of bodily action is missing in mere behavior? But what is an analogous question for mental action? I ask this: what ingredient of active, goal-directed thought is missing in mind-wandering? My answer: attentional guidance. Attention is guided when you would feel pulled back from distractions. In contrast, mind-wandering drifts between topics unchecked. My unique starting point motivates new accounts of four central topics about mental action. First, its causal basis. (...) Mind-wandering is a case study that allows us to tease apart two causes of mental action––guidance and motivation. Second, its experiential character. Goals are rarely the objects of awareness; rather, goals are “phenomenological frames” that carve experience into felt distractions and relevant information. Third, its scope. Intentional mind-wandering is a limit case of action where one actively cultivates passivity. Fourth, my theory offers a novel response to mental action skeptics like Strawson. (shrink)