Some very persuasive arguments have been put forward in recent years in support of the disunity of science. Despite this, one is forced to acknowledge that unification, especially the practice of unifying theories, remains a crucial aspect of scientific practice. I explore specific aspects of this tension by examining the nature of theory unification and how it is achieved in the case of the electroweak theory. I claim that because the process of unifying theories is largely dependent on particular kinds (...) of mathematical structures it is possible to have a theory that displays a degree of unity at the level of theoretical structure without an accompanying ontological unity or reduction. As a result, unity and disunity can coexist not only within science but within the same theory. (shrink)