This study examined willingness to communicate (WTC) in English among Iranian EFL learners in the classroom context. For this purpose, a second language willingness to communicate (L2WTC) model based on WTC theory (MacIntyre, Clément, Dörnyei, and Noels, 1998) and empirical studies was proposed and tested using structural equation modeling (SEM). This model examined the interrelationships among WTC in English, communication confidence, motivation, classroom environment, attitudes toward learning English, and English language achievement. A total of 243 English-major university students in Iran completed a questionnaire. The proposed SEM model adequately fitted the data. Results of the SEM indicated that classroom environment was the strongest direct predictor of L2WTC; communication confidence directly affected WTC; motivation indirectly affected WTC through communication confidence; English language proficiency indirectly affected WTC through communication confidence; and the classroom environment directly affected attitudes, motivation, and communication confidence.