Previous research has shown that both depression and social anxiety--2 facets of internalizing psychopathology--are characterized by low levels of extraversion/positive emotionality (E/PE). However, little is known about the relations of the facets of E/PE with the symptoms of depression and social anxiety. This study utilized multiple measures of each facet of E/PE, as well as depression and social anxiety symptoms. Self-report data were collected from large samples of college students and psychiatric outpatients. Separate factor analyses in each sample revealed a 4-factor structure of E/PE consisting of Sociability, Positive Emotionality, Ascendance, and Fun-Seeking. Structural equation modeling revealed that, after controlling for the higher order internalizing factor and the overlap among the E/PE facets, social anxiety was broadly related to all 4 facets of E/PE, whereas depression was strongly related to only low positive emotionality. Implications for hierarchical models of personality and psychopathology, assessment and treatment, and etiological models are discussed. [ABSTRACT FROM AUTHOR]