This paper presents and analyzes lexical and syntactic evidence from heritage Russian as spoken by bilinguals dominant in American English. The data come from the Russian Learner Corpus, a new resource of spoken and written materials produced by heritage re-learners and L2 learners of Russian. The paper focuses on lexical phrase violations, which we divide further into transfer-based structures and novel creations, showing that the latter are used by heritage speakers, but generally not freely available to L2 learners. In constructing innovative expressions, heritage speakers follow general principles of compositionality. As a result, novel constructions are more semantically transparent than their correlates in the baseline or dominant language. We argue that such semantically transparent, compositional patterns are based on structures that are universally available across languages. However, L2 speakers resort to these universal strategies for creating novel phrases much less often than heritage speakers. In their linguistic creativity, heritage speakers’ utterances parallel those of L1 child learners rather than L2 speakers.