This article reports the findings of two meta-analyses that explored the relationship between teacher clarity and student learning. Combined, the results suggest that teacher clarity has a larger effect for student affective learning than for cognitive learning. However, neither the effects for cognitive learning nor affective learning were homogeneous. Heterogeneous effects were observed for several additional subsets of the datasets. The first meta-analysis reviews the findings of 144 reported effects (N = 73,281) examining the relationship between teacher clarity and student learning outcomes. The cumulative evidence indicates that teacher clarity accounts for approximately 13% of the variance in student learning. The second meta-analysis reports a random-effects meta-analysis of 46 studies (N = 13,501). Moderators were examined and revealed that study design (i.e., survey versus experiment) moderated the impact of instructor clarity on affective learning. No significant moderators were found for cognitive learning. The cumulative results confirm that teacher clarity has a moderate effect on student affective and cognitive learning; however, persistent heterogeneity among the samples implies the presence of one or more moderating variables. Theoretical, practical, and methodological implications are discussed. Recommendations are made for future clarity researchers including a shift back to using low-inference behavioral measurements instead of high-inference perceptual measurements.