This study examined effects of teaching assistant argumentativeness on student affective learning and perceptions of teacher power use. Significant differences were found in student affective learning for classes taught by low, moderate and high argumentative TAs. Lower TA argumentativeness is positively associated with student affective learning and vice versa. Significant differences were also found for student perceptions of instructor power use for classes taught by low, moderate, and high argumentative TAs. Lower TA argumentativeness is associated with higher levels of power use and vice versa. Multiple correlations revealed that TA and student argumentativeness accounted for 14% of the variance in student affective learning and for 15% of the variance in TA referent power use. Findings suggest that although high argumentative TAs may be “social specialists” in power use (and thus be perceived by students to use less power), their high levels of argumentativeness seem to have negative effects on student affective learning.