This study examines the effects of co-teaching between native and non-native English teachers on English as a foreign language (EFL) students' English proficiency in China, and then explores the students' perceptions of the collaborative form of teaching. Based on the co-teaching schemes created by the previous researchers, this experiment adopted three co-teaching models: (1) one teaching/one assisting model, (2) team teaching model, and (3) station teaching model. By comparing the effects of co-teaching with those of traditional teaching, the study found that the students who were co-taught by a native and a non-native English teacher made more gains in English proficiency than those who were taught by one teacher alone. The findings from the attitudinal survey indicate that the students generally held a positive attitude towards co-teaching and that they attributed the success of this experiment to three benefits in co-teaching: ideal linguistic environment, complementary teaching behaviors, and favorable cultural atmosphere.