A critical question about bilingualism is how two or more languages are processed in the bilingual mind (e.g., Kroll, Bobb, & Hoshino, 2014). Previous research shows that bilinguals' languages interact, at least at the lexical and phonological levels. Relatively little research has addressed whether this occurs at the syntactic level during sentence processing. One event-related potential study with Welsh-English bilinguals showed co-activation of syntactic properties of one language that affected processing of the other language (Sanoudaki & Thierry, 2014, 2015). The current study replicates Sanoudaki and Thierry with Spanish-English bilinguals, and the results largely reproduce their findings of syntactic co-activation during sentence processing. These converging results have implications for theories about bilingual language processing regarding how syntax may interact in the bilingual mind.