This thesis examines the roles of materials in the classroom ecology of one seventh-grade social studies Spanish immersion class. Research has shown that dual language and immersion (DLI) teachers often feel challenged to find and use appropriate materials effectively; however, no previous studies have used classroom-based data to examine the realities of the affordances provided by materials in the immersion classroom. Data were collected through classroom observation, audio-recordings, and teacher interviews. Findings revealed that the materials played central, and sometimes unexpected, roles in the classroom ecology. Their structures and uses often promoted a monologic, “one-correct-answer” instructional paradigm that led to limited language instruction, constrained student discourse, and fact-centered performances of knowledge. Based on these results, implications for overall language development, vocabulary instruction, materials development and immersion teacher education are discussed. Recommendations are also made for future research focusing on materials use in immersion classrooms.