A prominent but poorly understood domain of human agency is mental action, i.e., thecapacity for reaching specific desirable mental statesthrough an appropriate monitoring of one's own mentalprocesses. The present paper aims to define mentalacts, and to defend their explanatory role againsttwo objections. One is Gilbert Ryle's contention thatpostulating mental acts leads to an infinite regress.The other is a different although related difficulty,here called the access puzzle: How can the mindalready know how to act in order to reach somepredefined result? A crucial element in the solutionof these puzzles consists in making explicit thecontingency between mental acts and mentaloperations, parallel to the contingency betweenphysical acts and bodily movements. The paper finallydiscusses the kind of reflexivity at stake in mentalacts; it is shown that the capacity to refer tooneself is not a necessary condition of the successfulexecution of mental acts.