This paper studies mixed code-switched structures in bilingual discourse in the Erzya-Russian code-switching (ERCS) variety on the basis of unstructured interviews. It is argued that the matrix language frame model (Myers-Scotton 2002) cannot be applied to this variety, as the matrix language of the clauses cannot be identified unambiguously. The paper focuses on verbal constructions, numeral phrases, and time expressions, which are the most typical cases of composite structures having a bilingual grammatical frame. The analysis of these constructions shows that ERCS clauses have a composite matrix language and display traces of the language mixing phase on Auer’s 1999 continuum.