How positively or negatively people generally view others is key for understanding personality, social behavior, and psychopathology. Previous research has measured generalized other-perceptions by relying on either explicit self-reports or judgments made in group settings. With the current research, we overcome the limitations of these past approaches by introducing a novel measurement instrument for generalized other-perceptions: the Online-Tool for Assessing Perceiver Effects (O-TAPE). By assessing perceivers’ first impressions of a standardized set of target people displayed in social network profiles or short video sequences, the O-TAPE captures individual differences in the positivity of other-perceptions. In Study 1 (n = 219), the instrument demonstrated good psychometric properties and correlations with related constructs. Study 2 (n = 142) replicated these findings and also showed that the O-TAPE predicted other-perceptions in a naturalistic group setting. Study 3 (n = 200) refined the nomological network of the construct and demonstrated that the O-TAPE is invulnerable to effects of social desirability.