This study presents formant transition data from 21 speakers for the apical alveolar∼retroflex contrast in three neighbouring Central Australian languages: Arrernte, Pitjantjatjara, and Warlpiri. The contrast is examined for three manners of articulation: stop, nasal, and lateral /t ∼ ʈ/ /n ∼ ɳ/, and /l ∼ ɭ/, and three vowel contexts /a i u/. As expected, results show that a lower F3 and F4 in the preceding vowel signal a retroflex consonant; and that the alveolar∼retroflex contrast is most clearly realized in the context of an /a/ vowel, and least clearly realized in the context of an /i/ vowel. Results also show that the contrast is most clearly realized for the stop manner of articulation. These results provide an acoustic basis for the greater typological rarity of retroflex nasals and laterals as compared to stops. It is suggested that possible nasalization of the preceding vowel accounts for the poorer nasal consonant results, and that articulatory constraints on lateral consonant production account for the poorer lateral consonant results. Importantly, differences are noticed between speakers, and it is suggested that literacy plays a major role in maintenance of this marginal phonemic contrast.