People differ in how positively they tend to see others’ traits, but people might also differ in how strongly they apply their perceptual styles (Kenny et al., 2023). In two studies (Ns = 355, 303), the current research explores individual differences in how variable people’s first impressions are across targets (i.e., within-person variability), how and why these differences emerge, and who varies more in their judgments of others. Participants described themselves on personality measures and rated 30 (Study 1) or 90 (Study 2) targets on Big Five traits. Using the extended Social Relations Model (eSRM), results suggest that within-person variability in impressions is consistent across trait ratings. People lower in extraversion, narcissism and self-esteem tended to make distinctions across targets’ Big Five traits that were more consistent with other perceivers (sensitivity). Further, some people more than others tended to consistently make unique distinctions among targets (differentiation), and preliminary evidence suggests these people might be higher in social anxiety and lower in self-esteem and emotional stability. Overall then, a more complete account of person perception should consider individual differences in how variable people’s impressions are of others.