This chapter considers a central aspect of the relationship between immanent realism and states of affairs. Immanent realism, or Aristotelian realism, is the view that properties are universals, and that universals are somehow present 'in' their instances. In Scholastic terms, they are universalia in rebus. They contrast with transcendent universals, the universals of transcendent or Platonic realism, which 'transcend' their instances (universalia ante rem). If, like me, you are attracted to both realism about universals and naturalism (the doctrine that every entity exists in space and/or time), immanent realism is appealing, since it pulls universals out of 'Plato's heaven' and brings them 'down to earth'. A question worth asking is how they are brought down to earth, as it were. I call it the hosting question. This is a special case of the general issue of what it is for a universal to be instantiated.One traditional answer is that they are hosted by being constituents of 'bundles of universals' (see chapter 14, this volume). In this chapter, I shall explore the answer that they are hosted by being constituents of the states of affairs that result from their instantiations. I shall pay particular attention to two competing specific answers found in David Armstrong's middle period (late 1970's to late 1990's). For as well as being quite accessible, Armstrong of this period is, by far, the most important contemporary author on both immanent universals and states of affairs. 'Universal' is a well-known term. Roughly, a universal is a property or relation construed as a 'one over many' which is shared by the things that instantiate it (its instances).The notion of a 'state of affairs' is perhaps less familiar. In the most general sense, a state of affairs can be said to exist "if and only if a particular […] has a property or, instead, a relation holds between two or more particulars" (Armstrong 1997: 1). 1 For instance, the tomato's being red and John's loving Sam are states of affairs.The plan for the chapter is as follows. First, in section 2, I contrast immanent universals with transcendent universals, and consider whether they are concrete or abstract.1 Strictly speaking, a first-order state of affairs. Second-order states of affairs are when first-order states of affairs have properties or stand in relations (e.g. the tomato's being blighted causing it to be discarded), or when first-order properties and relations have properties or stand in relations (e.g. redness being a colour); and similarly for higher orders. As is common in the literature, this chapter deals only with first-order states of affairs.