Gurindji Kriol is a contact variety spoken in northern Australia which has been identified as a mixed language. Yet its status as an autonomous language system must be questioned for three reasons — (i) it continues to be spoken alongside its source languages, Gurindji and Kriol, (ii) it has a close diachronic and synchronic relationship to code-switching between Gurindji and Kriol, and (iii) its structure bears a strong resemblance to patterns found in this code-switching. Nonetheless, this paper presents criteria which support the claim of 'language-hood' for Gurindji Kriol. It is demonstrated that Gurindji Kriol (i) is a stable language variety (it has child language learners and a high degree of inter-speaker consistency), (ii) has developed independent forms and structural subsystems which have not been adopted back into the source languages, and (iii) contains structural features from both languages which is rare in other language contact varieties including Kriol/Gurindji code-switching. The paper also presents a number of structural indicators which can be used to distinguish Gurindji Kriol mixed language clauses from code-switched clauses.