We explore the impact of crosslinguistic influence in first language (L1) attrition, changes in an individual’s L1 due to exposure to additional languages. We report an experiment examining reference production in Mandarin in a picture description task by native Chinese speakers residing in Italy or Spain. Mandarin allows null subjects, where subjects can be expressed with a null or overt pronoun; previous work shows that L1 Mandarin speakers exposed to English use more overt pronouns in Mandarin than their more-monolingual peers. In the study reported here, despite exposure to two languages (Italian and Spanish) that, unlike English, allow null subjects, our multilingual speakers used fewer null pronouns and more overt pronouns than their more-monolingual Chinese peers. These findings contribute to attrition research by disentangling the impact of crosslinguistic influence in L1 attrition, and provide insights into the effect of bi- and multilingualism on linguistic systems.