Infants develop language-specific biases favoring either consonantal or vocalic information. These phonological biases affect various levels of spoken-language recognition in children and adults. This study explored whether adults who speak a second language (L2) apply phonological biases during L2 lexical processing, and whether the biases applied are those of the native language (L1), or those appropriate for the L2. Two word reconstruction experiments were carried out in English and Mandarin Chinese. L1 and L2 speakers of English demonstrated a consonantal bias by changing English vowels faster than consonants. L1 and L2 speakers of Mandarin demonstrated a vocalic bias by changing Mandarin consonants faster than vowels. Even relatively late L2 classroom learners whose L1 triggers a consonantal bias (English) exhibited a vocalic bias in their L2 (Mandarin). Lexically related processing biases are thus determined by the phonological and lexical characteristics of the stimuli being processed and not solely by listeners’ L1.