This study explores variation in willingness to communicate (WTC) in English between whole-class interaction and dyadic and group interaction, and teacher interaction strategies identified to sustain students' WTC in whole-class interaction that primarily followed the initiation-response-feedback (IRF) pattern. Data were collected from a regular English class at a university in China through audio-recording of a lesson, classroom observation, self-rating of WTC by 23 students, and stimulated recall interviews with four focal students. The results indicate that WTC in whole-class interaction did not significantly differ from WTC in dyadic and group interaction. Teacher interaction strategies, including the use of open or referential questions in the I-move and F-move, manipulation of wait time following prompts, and monitoring private speech and contextual or multimodal clues of students' WTC, functioned to sustain classroom WTC. Implications for adopting teacher interaction strategies in line with lesson plans within the framework of IRF pedagogic discourse are discussed.