This study investigated the critical roles of school climate and efficacy (collective teacher efficacy and teacher self-efficacy) in teachers' enthusiasm throughout their teaching careers. Based on multigroup structural equation modelling and mediation analysis of a sample of 4594 primary school teachers in China, this study found that school climate significantly affected teachers' enthusiasm. Furthermore, collective teacher efficacy had a stronger mediating effect than teacher self-efficacy on the relationship between aspects of school climate and teachers' enthusiasm. Among the four aspects of school climate, teachers' perception of student relations had the strongest influence on novice, mid-and late-career teachers' enthusiasm. Moreover, the practical implications of the findings for improving teachers' enthusiasm at different stages of their careers are discussed.