Possessive (‘have’) clauses with indefinite possessees are surveyed in three now-extinct languages of the Oregon coast–Alsea, Hanis Coos, and Miluk Coos. Adjectival or verbal denominals marked by prefix-suffix combinations are employed when the possessee is unmodified; when it is modified, a different construction is used in which the modifier is treated as the clause predicate. Similar constructions also express existence and location of unpossessed entities. Negative possession and negative existentials involve negators distinct from ordinary negation, but the syntax of these differs in Alsea versus Hanis and Miluk. Few or no other languages in the southerly Northwest Coast show quite the same configuration of constructions as either Alsea or Hanis and Miluk.