Previous research on language mixing has revealed similarities in written and oral production with respect to syntactic and pragmatic patterns (e.g. Callahan 2004). This study finds however, that the two modes of expression diverge in loanword gender assignment. English-origin NPs inserted into written Spanish discourse (e.g. un baggie) were analyzed and compared to English-origin NPs in oral Spanish discourse. Results showed that loanwords are assigned feminine gender at significantly higher rates in written than in oral data. Also, the study shows that the reasons for assigning feminine gender are different for written and oral production. Phonological factors appeared to be influential in the oral, but not written, data. The `analogical criterion', according to which the gender of the Spanish translation equivalent determines the gender assigned to the loanword, e.g. una letter (una carta), was a strong predictor of feminine gender in the written data, but had a weaker effect in the oral data.