Hylomorphism is the theory that objects are composites of form and matter. Recently it has been argued that form is structure, or the arrangement of an object's parts. This paper shows that the principle of form cannot be ontologically exhausted by structure. That is, I deny form should be understood just as the arrangement of an object's parts. I do so by showing that structure cannot play the role form is supposed to in a certain domain of objects, specifically, in (...) mereological simples. Thus, I show that Hylomorphism does not reduce to Structuralism. I also draw out some important consequences from my argument for Hylomorphism in general. (shrink)