An Inventory of Interpersonal Strengths (IIS) was developed and validated in a series of large college student samples. Based on interpersonal theory and associated methods, the IIS was designed to assess positive characteristics representing the full range of interpersonal domains, including those generally thought to have negative qualities (e.g., introversion, coldness, submissiveness). The 8 subscales (octants) of the 64-item IIS demonstrated good circumplex features and reliability. Tests comparing Big 5 interpersonal factors, Inventory of Interpersonal Problems (IIP), Battery of Interpersonal Capabilities (BIC), and other interpersonal measures demonstrated convergent and discriminant validity and shared interpersonal structure. The IIS accounted for significant additional variance in life satisfaction and quality of personal relationships beyond the IIP and the BIC. (Contains 7 tables and 4 figures.)