This paper examined the influence of L2 (second/foreign language) competence, classroom environment and emotions on and causes for Chinese young learners' willingness to communicate (WTC) and participation in EFL (English as a foreign language) class. The respondents were 375 middle school students who answered a mixed-form survey. The major findings were: a) both WTC and participation in EFL class were significantly correlated with L2 competence, classroom environment and emotions, b) L2 competence, classroom environment and emotions significantly predicted the students' WTC and participation in EFL class respectively, and c) eight major types of causes were reported to affect the students' WTC and participation in EFL class respectively: Linguistic, psychological, interest, peer, teacher, personality, task difficulty/familiarity and other factors. These findings clearly pinpoint the importance of L2 competence, classroom environment and emotions in influencing WTC and participation in EFL classroom interactions.