 In  Section 1  we will explore the metaphysical distinction between stuff and things, and examine the linguistic data used to make the mass-noun/count-noun distinction, and show how it has been used to motivate the metaphysical distinction. In  Sections 2  and  3,  we will survey different answers to our main target question: “what do nominal mass expressions refer to?” Lastly, after examining the linguistic data and the metaphysical theories, in  Section 4  we will examine whether the metaphysical stuff/thing distinction is well-motivated by the linguistic mass/count distinction, and whether the latter is up to the tasks assigned to it by metaphysicians.