In this study I explored the relationships among the locus of control, self-efficacy, and subjective well-being (SWB) of elementary school teachers in China, with a focus on the mediating effect of self-efficacy in the relationship between external locus of control and SWB. A survey was conducted with 305 elementary school teachers using the Adult Nowicki-Strickland Internal-External Locus of Control Scale, the General Self-Efficacy Scale, and SWB measurements. External locus of control was found to be negatively correlated with SWB, and selfefficacy was positively correlated with SWB. Structural equation modeling analysis showed that self-efficacy partially mediated the effect of external locus of control on SWB, with the indirect effect accounting for 36.34% of the total explained variance. Promoting a sense of control and self-efficacy may be effective in improving elementary school teachers' SWB.