Psychological essentialism theory explains how and why some social groups are described as holding an invariant, group-defining ‘essence’. Drawing on naturally-occurring talkback radio conversations, this paper shows how speakers assign essentialised cultural or tribal qualities to Sudanese refugees, to explain their brutal conduct both in Sudan and in Australia. It is asserted that essentialist ontologies can be set on implicit lay theories, causally relating culture to conduct, and functioning ideologically as rationalisations for intolerant and racist goals. A discursive approach yields insights into the subtle psychological essentialism practice in everyday speech.