The feeling that we are agents, intentionally making things happen by our own actions, is foundational to our understanding of ourselves as humans. People's metacognitions of agency were investigated in 4 experiments. Participants played a game in which they tried to touch downward scrolling Xs and avoid touching Os. Variables that affected accuracy included speed of the scroll, density of the targets, and feedback. Of central interest were variables directed not only at accuracy but also at people's control: the turbulence of the cursor and how close the cursor had to come to the target for a hit (i.e., "magic"). After each trial, people made judgments of agency or judgments of performance. People were selectively sensitive to the variables to which they should be responsive in agency monitoring--whether the cursor moved in close synchrony to their movements and whether targets disappeared by magic. People knew, separably from their objective or judged performance, when they were in control and when they were not. These results indicate that people can sensitively monitor their own agency.