Abstract: The study probes into the cross-linguistic influence on Cantonese-English bilingual children’s interpretation of subject and object relative clauses (RCs). Data show that bilingual children perform significantly better on subject RCs, though monolingual children perform as well in subject RCs as in object RCs. The results of error analyses indicate that bilingual children were accurate in assigning thematic roles in object RCs, but unable to select accurately subject RCs as the head referent because both Cantonese and English allow SVO order, contradictory to the object RC analysis. Our data verify Yip & Matthews’ (2007) argument that cross-linguistic influence was due to word order overlap and extend the observation to older children at the group level in comprehension. The two systems of bilingual children have significant interaction in comprehension, even after early childhood. Besides, our regression analyses confirm the importance of dominant language in cases of individual children.