The purpose of this qualitative case study was to explore through the lens of culturally responsive instruction (CRI) the development of teachers’ sense of efficacy, as defined by Bandura (1995), to address the literacy learning of diverse first, second, or third grade (i.e., primary grade level) students. In this process, I purposively selected the location and the participants because answering my research questions required that I conduct the investigation within learning settings where culturally and linguistically diverse students in the primary grade levels (i.e., first, second, or third grade) receive literacy instruction. My time in the field and my comprehensive focus on the participants and their teaching practices allowed me to gather rich descriptive data concerning the participants’ perspectives, experiences, and teaching practices through multiple traditional case study data collection means. Four overarching themes emerged from within, between, and across case analysis as significant in the development of teachers’ sense of efficacy to address the literacy learning of their pluralistic student populations in a culturally responsive manner. The themes include: (1) Perspectives shaping literacy instruction provision, (2) Understanding what constitutes CRI, (3) The impact of establishing a collaborative teaching community on the development of teachers’ sense of efficacy, and (4) Foundations of culturally responsive teachers’ sense of efficacy. I base my recommendations for the development of inservice teachers’ sense of efficacy to address the literacy learning of their students using CRI and my recommendations for future research on my study findings.