The subject of bilingual language use in the southwestern United States has been widely researched. However research pertaining to the Phoenix Metropolitan area is lacking. Studies have shown that language choice is governed by linguistic as well as social constraints (Gumperz, 1977; Poplack 1980; 1981). This study examined and compared the code-switching behaviors of two communities in the southwestern United States: Antonito, Colorado and the Phoenix Metropolitan area in Arizona. The study explored the social and linguistic factors that are said to govern code-switching behaviors such as the type of switches made (intra-sentential or single lexical switches), the position in the utterance where the switch occurs (final or other), the direction of the switch (an utterance beginning in English and ending in Spanish, or beginning in Spanish and ending in English), the gender and level of education of the participants (college or above; high school or below), the ethnicity of the interviewer (Anglo or Hispanic), as well as which of the aforementioned social and linguistic factors most favored intra-sentential switches. The study used corpus data, with four participants from each community for a total of eight interviews. Participants from each corpus were selected to control for gender, the highest level of education achieved and the ethnicity of the interviewer. The study found that in the corpora looked at, linguistic factors such as position of the switch and direction of the switch affected intra-sentential switches more than social factors, although in terms of frequencies within individual factor groups, social factors such as the ethnicity of the interviewer, and the participant's level of education were found to be significant in affecting code-switching behavior.