After Umberto Boccioni's death in 1916 one of his most famous works, the plaster sculpture Unique Forms of Continuity in Space, was cast in bronze on multiple occasions. These copies were disseminated to many prominent museums and bronze came to be seen as the original medium of the work by the general public. In this paper I argue that plaster, as a material, more accurately represents the artistic intent of Boccioni than the bronze copies that followed his passing through a mixture of visual analysis and textual evidence. I also call attention to the provenance of the sculpture, in both its plaster and bronze forms, in an attempt to proliferate the fact that the original work is plaster as well as to critique the ethics of museums that choose to display its bronze iterations. I conclude that the Tate Modern is the only museum that currently displays a bronze Unique Forms of Continuity in Space ethically due to its open and accurate acknowledgement of the work's history as a posthumous copy.