In his Athanasia, the main source of his metaphysics, Bolzano deals with the problem of the freedom of the human will. This paper reconstructs two definitions of free will and focuses on Bolzano’s arguments and counter-arguments for and against the existence of free will. These arguments are confronted with some aspects of the modern discussion of this subject. The paper examines especially how far the so called principle of alternate possibilities is relevant for a better understanding of Bolzano’s arguments. Assuming the reconstructed definitions of the freedom of the will, it turns out that a person has only free will if this person could have wanted otherwise. But, according to Bolzano’s view in the Athanasia, the possibility to want otherwise is not a necessary condition for moral responsibility. Finally, the paper shortly discusses whether, for Bolzano, people are free after death and whether God is free.