The authors developed and evaluated the psychometric properties of the 18-item Personal Acquaintance Measure (PAM) and investigated how the PAM relates to self- other agreement in personality ratings. Results support that 6 factors represent the PAM (Duration, Frequency of Interaction, Knowledge of Goals, Physical Intimacy, Self-Disclosure, Social Network Familiarity), which showed evidence of internal consistency, test-retest reliability over 3 weeks, sensitivity to known group differences, discriminant validity from socially desirable responding, and convergent validity with other relationship inventories. Results also show that the PAM positively predicted self-other agreement. The authors discuss the implications of these findings for the PAM and research in person perception, although this measure may also be used in other research areas.