The structure of the Hypomanic Personality Scale was explored in a sample of young adults (N = 884); resulting structures were validated on subsamples with measures of personality traits, internalizing symptoms, and externalizing behaviors. Hierarchical cluster analysis and estimates of general factor saturation suggested the presence of a weak general factor, as well as 3 subordinate clusters. The 3-cluster subscales (Social Vitality, Mood Volatility, and Excitement) were moderately correlated but conceptually distinct and were correlated in opposing patterns with a range of personality and psychopathology measures. Results show that cluster subscales suppress total score associations with validity measures. Recommendations are made to analyze Hypomanic Personality Scale data by subscale, and theoretical implications are discussed. (Contains 1 figure, 4 tables and 4 footnotes.)