In Kuuk Thaayorre, ergative marking is of both syntactic and pragmatic import. Syntactically, ergative inflection marks a noun phrase as the subject of a transitive clause. Though this may be considered definitional of an ergative morpheme, Kuuk Thaayorre joins a growing number of languages in which ergative marking is documented to be “optional”; not obligatorily present in all transitive clauses. Conversely – and more unusually – the subject of a Kuuk Thaayorre intransitive clause may in some cases be ergative-marked. This paper proposes that as well as signifying the ergative case relation, the ergative morpheme’s presence in an intransitive clause signals that the subject referent is “unexpected”, and its absence from a transitive clause signals that the subject referent is “expected”.