Warrwa is a morphologically ergative language with three ergative markers, -na, -ma, and-nma. Intriguingly, while -ma is almost in complementary distribution with both -na and -nma, the latter pair are in "free variation'', and either can replace the other anywhere. When it is used, however, -nma accords prominence to an Agent (i.e. transitive subject), singling it out asboth unexpected and highly agentive; accordingly it can be considered to be a focal ergative marker.By contrast, -na is an ordinary ergative marker, with no pragmatic components to its meaning; the situation for -ma is uncertain. The story is complicated further by the fact that ergative markers are occasionally omitted from Agent NPs. This ‘"optional'' ergative marking is not random: it defocusses the Agent, indicating that it is both expected and low in agentivity. Much of the paper is taken up by presentation of evidence for, and explication of, these claims based on an examination of the distribution of the markers in a corpus of mostly narrative texts. An attempt isalso made to explain the system of marking of Agent NPs in Warrwa, and situate it in relation to otherlanguages.