This article seeks to contribute to the ongoing debate on the dimensionality of the burnout syndrome. Specifically, its aims are: (1) to investigate the role of efficacy beliefs using negatively worded inefficacy items instead of positive ones and (2) to establish whether depersonalization and cynicism can be considered two different dimensions of the teacher burnout syndrome. The results show that, compared with efficacy beliefs, inefficacy beliefs relate more strongly to the other burnout dimensions considered by the study (i.e., emotional exhaustion, depersonalization, and cynicism). Moreover, using partial disaggregation method, a better fit is found for the four-factor model with separate depersonalization and cynicism dimensions than for the three-factor model in which depersonalization and cynicism are collapsed into one factor. The article concludes that future research on teacher burnout should: (1) use the inefficacy scale as the "third dimension" of burnout, rather than the efficacy scale, and (2) include the cynicism and depersonalization constructs.