Students' first and target language are often used by both teachers and students during instruction in the foreign language classroom (Levine, 2011). In this study, the frequency of and reasons for students' and teachers' use of English or Spanish were analyzed using video recordings of 40 class sessions taught by eight randomly selected Spanish 102 teachers and by eight randomly selected Spanish 202 teachers. All of the videos were transcribed, and a word count was made to determine the overall use of Spanish and English by the students and teachers. The relationship between the number of code-switches by teachers and students and the overall use of Spanish and English in the classroom were analyzed. Finally, the code-switches between languages were categorized and counted to determine if students or teachers initiated the switch and under what circumstances, as well as the influence of code-switching on the interlocutor's subsequent language choice. The results indicate that teacher-initiated code-switches had the most influence on students' subsequent language choice and that teachers code-switched more often, even though students used a higher overall percentage of the first language. In addition, there was a strong positive relationship between the number of code-switches and the overall use of Spanish and English during instruction.