The research design applied in this study was a convergent parallel mixed-method approach that included qualitative and quantitative data collection. The quantitative data accrued through the Teacher's Sense of Efficacy Survey (TSES) survey. The quantitative data also included a collection of English language learner's reading-proficiency-level scores from a large-scale English-language proficiency test: Assessing Comprehension and Communication in English State-to State for ELLs 2.0 (ACCESS for ELLs 2.0) administered in 2017. The quantitative data from the TSES survey and the ACCESS test were analyzed using the Pearson correlation coefficient. Findings from the TSES indicated that teachers had much self-efficacy in implementing classroom-management strategies and instructional strategies but less self-efficacy in implementing student-engagement activities. Findings from the ACCESS test data revealed no significant relationship between any of the survey composite results and reading proficiency-level scores from the ACCESS test results at p < .05. Findings also showed no significant relationship between teacher perceptions of their self-efficacy and students' reading proficiency-level scores at p < .05. The qualitative analysis---the open-ended questionnaire data---were analyzed using themes, codes, statistical frequency, and proportions. Findings from the qualitative data reflected that teachers felt higher self-efficacy when implementing classroom-management techniques and instructional strategies and lower self-efficacy implementing student-engagement activities.