--- - |2+ Abstract Objective What is gained by having others report on one’s personality? Research on adult samples has suggested that informant reports are especially informative regarding traits that are highly visible and evaluative (i.e., socially desirable/undesirable instead of neutral), such as Openness, Conscientiousness, and Agreeableness. This 18‐year longitudinal study aims to demonstrate the unique predictive power of other‐rated personality in adolescence, using life outcomes and personality in adulthood as trait criteria. Method We examined the unique predictive power of self‐ and other‐rated Big Five personality traits at age 12 and 17 on self‐rated life outcomes and personality at age 29 (e.g., educational achievement, work income, depression, moral transgressions, and relationship satisfaction). Participants were 186 German adolescents (53% boys), their parents and friends at age 12, and their mothers and fathers at age 17. Results Other‐ratings showed unique predictive power beyond self‐ratings for all Big Five traits, with the most consistent results for Openness, Conscientiousness, and Agreeableness. Conclusions Results demonstrate the added value of including other‐reports on adolescent personality when predicting future life outcomes and personality, especially for highly visible and evaluative traits. The present study sheds light on the predictive power of self‐ versus other‐rated personality and personality–outcome associations. - Journal of Personality, EarlyView.