Gurindji Kriol and Light Warlpiri are two mixed languages spoken in northern Australia by Gurindji and Warlpiri people, respectively. Both languages are the outcome of the fusion of a contact variety of English (Kriol/Aboriginal English) with a traditional Australian Aboriginal language (Gurindji or Warlpiri). The end result is two languages which show remarkable structural similarity. In both mixed languages, pronouns, TMA auxiliaries and word order are derived from Kriol/Aboriginal English, and case-marking and other nominal morphology come from Gurindji or Warlpiri. These structural similarities are not surprising given that the mixed languages are derived from typologically similar languages, Gurindji and Warlpiri (Ngumpin-Yapa, Pama-Nyungan), and share the Kriol/Aboriginal English component. Nonetheless, one of the more striking differences between the languages is the source of verbs. One third of the verbs in Gurindji Kriol is derived from Gurindji, whereas only seven verbs in Light Warlpiri are of Warlpiri origin. Additionally verbs of Gurindji origin in Gurindji Kriol are derived from coverbs, whereas the Warlpiri verbs in Light Warlpiri come from inflecting verbs. In this paper we claim that this difference is due to differences in the complex verb structure of Gurindji and Warlpiri, and the manner in which these complex verbs have interacted with the verb structure of Kriol/English in the formation of the mixed languages.