High-frequency words are processed faster than low-frequency words, known as the word frequency effect (FE). Although the FE has been studied in various writing systems as well as in first- (L1) and second-language (L2) reading, existing theoretical hypotheses are mainly based on findings in alphabetic languages. To date, no study has investigated theoretical explanations of the FE such as the learning hypothesis, the lexical entrenchment hypothesis and the rank hypothesis apply to Chinese-English bilinguals. The present study, therefore, compared the FEs in Chinese- and Dutch-English bilinguals during natural paragraph reading in their L1 and L2, using eye-tracking measures. Chinese bilinguals exhibited a larger FE in L2 than in L1. They displayed smaller L1 FEs and much steeper L2 FE curves than Dutch bilinguals. These findings are not entirely consistent with the existing FE hypotheses, and the present study discusses theoretical accounts in light of the observed results.