Objectives: Teacher talk provides the medium for teaching and learning. However, there has been little emphasis on conceptualizing and measuring teacher talk within specific contexts and populations or the influence that child behavior has on teacher talk. We described and investigated varying models of teacher talk directed individually toward autistic students within 96 special education mathematics activities drawn from larger mathematics lessons. We also examined child behavior within mathematics contexts measured through observation and via teacher report. Methods: Our participants included 39 preschool–third-grade teachers across 14 districts in California and their 66 autistic students (Mage = 6.74 years, SD = 2.04). We utilized archival video observations from the start of the school year collected as part of a longitudinal study examining a classroom-based intervention for autistic students. Results: Our findings provide support for a five-factor model of teacher talk (instructional talk, questioning techniques, responsive language, directive language, and foundational talk) and shed light upon teachers’ overuse of directive language to direct or redirect autistic students’ behavior relative to the other talk dimensions. We also documented a significant positive association between teachers’ use of non-task-related directives and student emotion dysregulation. (author abstract)