This chapter is about Williams’s concept of an abstract particular (or trope) and how he arrived at the notion of a trope through a certain theory of what an abstract entity is and of what abstraction is. Even though an entity is abstract it does not follow that it is universal. An entity can be abstract and particular (i.e., not universal). A trope is an abstract particular nature. Various influences from past philosophers, such as E.B. McGilvary and G.F. Stout, on his concept of tropes are covered, along with an explanation of how tropes build a parsimonious one-category ontology. Williams’s account of the distinction between abstract and concrete is presented as well as the distinction between abstractive and partitive analysis, which underpins how an object can be analysed in two different ways, namely, into its abstract and concrete parts.