Research suggests effective professional learning communities (PLCs) enhance teacher collaboration and student achievement. Some studies indicate that these communities also predict greater collective efficacy, while others suggest teacher efficacy is predictive of teachers working together. Although studies have identified effective, research-based PLC practices, how these specific practices effect collective efficacy has not been thoroughly studied. This study, using structural equation modeling (SEM), investigated the relationship between PLCs and teachers' collective efficacy drawing on 310 surveys from 16 schools in 1 district that had systematically implemented PLCs. Our findings showed that higher functioning PLCs predict higher levels of teacher collective efficacy (TCE). This suggests that engaging and supporting teachers in PLC work, as this district did, can lead to enhanced collective efficacy, which in turn can contribute to improved student achievement.