This study investigated teachers' efficacy and implementation in the context of a supplemental intervention for struggling adolescent readers. It examined teachers' efficacy at the start of their intervention training and investigated relationships among teachers' efficacy, implementation, and students' reading progress. The efficacy and implementation of 9 sixth-grade teachers and 11 ninth-grade teachers were compared, and student achievement gains were explored. Sixth-grade teachers had higher levels of efficacy, while ninth-grade teachers had higher levels of implementation. Findings indicated teacher efficacy was positively related to students' reading comprehension and overall reading achievement. Implementation was positively related to students' growth in vocabulary. (Contains 6 tables.)