According to self-determination theory, when teachers establish an autonomy supportive climate in the classroom, students demonstrate high levels of self-determination and are intrinsically motivated. The aim of this study was to identify factors leading teachers (N=336) to report that they create such a climate. We conducted a path analysis in order to examine the respective roles of teachers' implicit theories, their seniority, and their perceptions of pressures at work. We also attempted to find out whether these personal and contextual variables have a direct infiuence or are mediated by teachers' self-efficacy. Our first finding was that a theory of academic ability as a fixed trait caused a drop in the teachers' reported support for autonomy. On the other hand, the belief that academic abilities can be improved through students' own efforts indirectly favored an autonomy supportive climate by acting positively on the teachers' self-efficacy. Also, seniority had a significant positive effect on autonomy support that was direct, but was also mediated by self-efficacy. Finally, perceived pressures had a negative impact on reported autonomy support, but their infiuence was also mediated by self-efficacy.