The following study analyzes the frequency and nature of Spanish-English code-switching found in both the natural and planned speech (i.e. film) of Mexican-Americans. It investigates and compares the form, frequency, and function of code-shifts in four hours of recorded bilingual conversation obtained from the radio station, KXOL-FM Latino 96.3 (based out in Los Angeles, California) with the code-shifts found in Cardoso's (2003) film, Real Women Have Curves. Particular attention is given to what type of code-switching occurs in the recordings (whether it is intersentential switching or intrasentential switching) and specifically where those distinct types of code-shifts occur during communication. The environment, or speech acts, in which the code switches take place is also examined. The overarching purpose of this study is to uncover, explain, and compare the grammatical rules and socio-pragmatic functions of Spanish-English code-switching found in both natural and planned speech.