This study investigates the role of code-switching (CS) between Turkish (L1) and English (L2) in Turkish EFL (English as a foreign language) classroom interaction. It aims at describing and analyzing the pedagogical functions and sequential organization of CS in teacher talk. The research draws on the recordings of four intermediate level listening/speaking lessons collected at Yildiz Technical University in Istanbul, Turkey. CS examples from the transcriptions are analyzed according to functional analyses of Discourse Analysis (DA) and sequential analysis of Conversation Analysis (CA). The findings reveal that teachers code-switch to L1 for thirteen pedagogical functions: ensuring comprehension, checking comprehension, elicitingL1 equivalent, giving expanded explanation, giving feedback, classroom management, shift to main topic, encouraging learners to use L2, for humour, dealing with procedural trouble, time management, expressing cultural identity and providing metalanguage information. The findings also show that there is a systematic preference organization in CS in teacher talk.