This project investigates Spanish-English language mixing, a.k.a. Spanglish. The investigation aims to compare and contrast spoken and written data of this language contact phenomenon and test hypotheses about code switching among fluent bilingual and Spanish-dominant bilinguals. With regard to the former aim, the spoken data has been collected in a fieldwork in New York City, and is compared and contrasted to the written testament of this mix Pollito Chicken by Ana Lydia Vega. Through the description and analysis of these data sets the present thesis shows that there are both similarities and differences between spoken and written Spanish-English language mixing. The conclusion of the former aim is that, while Ana Lydia Vega manages to capture many features of spontaneous spoken Spanglish, there are also features present that are not typical of the spoken data in the investigation. With regard to the second aim, the investigation shows that a revision of generalizations about fluent bilinguals and Spanish-dominant bilinguals bilinguals might be in order.