This paper examines patterns in an Estonian–English bilingual child’s spontaneous speech, employing a computational application of the traceback method, which is used in usage-based linguistics. Forty-five hours of data were analyzed to check what proportion of patterns from code-mixed utterances are attested in the child’s monolingual data and in her input. Pattern overlap between the child’s and the caregivers’ speech was also examined. Results show that about one-third of code-mixed utterances can be traced back to the child’s input and one-third also to her own monolingual data. A little over half of the child’s utterances are either chunks or frame-and-slot patterns from the caregivers’ speech. These results make it evident that the traceback method can also be applied to language pairs that are genealogically more distant, though limitations exist.