Purpose: To examine whether improved speech recognition during linguistically mismatched target-masker experiments is due to linguistic unfamiliarity of the masker speech or linguistic dissimilarity between the target and masker speech. Method: Monolingual English speakers (n = 20) and English-Greek simultaneous bilinguals (n = 20) listened to English sentences in the presence of competing English and Greek speech. Data were analyzed using mixed-effects regression models to determine differences in English recogition performance between the 2 groups and 2 masker conditions. Results: Results indicated that English sentence recognition for monolinguals and simultaneous English-Greek bilinguals improved when the masker speech changed from competing English to competing Greek speech. Conclusion: The improvement in speech recognition that has been observed for linguistically mismatched target-masker experiments cannot be simply explained by the masker language being linguistically unknown or unfamiliar to the listeners. Listeners can improve their speech recognition in linguistically mismatched target-masker experiments even when the listener is able to obtain meaningful linguistic information from the masker speech.