Numerous studies have shown that bilinguals presented with words in one of their languages spontaneously and automatically activate lexical representations from their other language. However, such effects, found in varied experimental contexts, both in behavioural and psychophysiological investigations, have been essentially limited to the lexical-semantic domain. Using brain potentials in a mental decision task in early highly proficient Welsh–English bilinguals and English monolingual controls, a recent study suggests that language non-selective effects exist in the domain of syntax. In this paper, we test whether syntactic access in bilinguals is affected by relative language abilities, as indexed by verbal fluency measures in the bilingual's two languages. Results reveal that non-selective syntax in English sentence comprehension is limited to bilinguals with higher Welsh verbal fluency. This result suggests for the first time directionality in cross-language syntactic activation in early bilinguals.