While opinions on the semantic analysis of generics vary widely, most scholars agree that generics have a quasi-universal flavor. However, there are cases where generics receive what appears to be an existentialinterpretation. For example, B's response is true, even though only theplatypus and the echidna lay eggs: (1) A: Birds lay eggs. B: Mammals lay eggs too. In this paper I propose a uniform account of the semantics of generics,which accounts for their quasi-existential readings as well as for their more (...) familiar quasi-universal ones. Generics are focus-sensitiveoperators: their domain is restricted by a set of alternatives, which may be provided by focus. I claim that, unlike otherfocus-sensitive operators, generics may, but do not have to, associate with focus. When alternatives are introduced, either by focus or by other means, generics get their usual quasi-universal readings. But when no alternatives are introduced, quasi-existential readings result.I argue that generics, unlike adverbs of quantification, do not introduce tripartite structures directly, but are initially interpreted as cases ofdirect kind predication. Only when this interpretation fails to make sense, the phonologically null generic quantifier is derived, and tripartite structures result. This two-level interpretation has the effect that while adverbs of quantification require focus to determine which elements go to the restrictor and which to the nuclear scope, and hence must associate with focus, generics do not, and hence may fail to associate with focus, resulting in quasi-existential readings. (shrink)