There is ample evidence that speakers’ linguistic knowledge extends well beyond what can be described in terms of rules of compositional interpretation stated over combinations of single words. We explore a range of multiword constructions (MWCs) to get a handle both on the extent of the phenomenon and on the grammatical constraints that may govern it. We consider idioms of various sorts, collocations, compounds, light verbs, syntactic nuts, and assorted other constructions, as well as morphology. Our conclusion is that MWCs highlight the central role that grammar plays in licensing MWCs in the lexicon and the creation of novel MWCs, and they help to clarify how the lexicon articulates with the rest of the grammar.