The main purpose of this study was to investigate the current status of elementary school substitute teachers’ perceptions of their teaching commitment and teaching effectiveness, as well as to examine the effects of background factors on these perceptions. In addition the study sought to assess the effects of substitute teachers’ perceptions of their teaching commitment on their perceptions of their teaching effectiveness. A survey method was employed using two instruments, a questionnaire of elementary substitute teacher’s teaching commitment and a questionnaire of elementary substitute teacher’s teaching effectiveness. A total of 335 elementary school substitute teachers were selected using a stratified random sampling method (according to school size) in the Yunlin and Chiayi districts, and 276 valid questionnaires were obtained. Statistical methods were applied to analyze the data, including descriptive statistics, t-tests, one way ANOVA, Pearson’s product-moment correlation, simple regression, and simultaneous regression analysis. The main findings of the study were as follows: First, in the Yunlin and Chiayi districts, elementary substitute teachers’ perceptions of their teaching commitment and teaching effectiveness were above the average level. Second, there were statistically significant differences in the targeted elementary teachers’ perceptions of teaching effectiveness related to the variable of school size, while no significant difference was found among other factors. In addition, there was a significantly positive correlation between targeted teachers’ perceptions of their overall teaching commitment and their overall teaching effectiveness. Finally, elementary school substitute teachers’ perceptions of their overall teaching commitment had a predictive power of 46.3% on their perceptions of their overall teaching effectiveness, while the four subscales of teaching commitment had a predictive force of 50.2% on overall teaching effectiveness; among these, the “teaching involvement” sub-scale had the greatest influence.