This paper investigates the syntactic and semantic restrictions on modal adjectives that appear in prenominal and postnominal position in English, as in The stars visible include Capella. It is argued that, contrary to many current approaches, such adjectives are not implicit relative clauses. It is proposed that such adjectives instead constitute an exceptional lexical class, and form a complex head with determiners that license resource situations. A novel compositional semantics for these expressions is offered which exploits the dependence on resource situations in the logical representation.