||Hoelzle and Meyer (2009) found that the internal structure of the Personality Assessment Inventory (PAI; Morey, 2007) contains three components that they labeled internalizing, externalizing, and agentic surgency. This study aimed to validate the internalizing and externalizing dimensions of the PAI by assessing their theoretical and empirical relationships to traits from the Five Factor Model (FFM). The sample consists of 536 undergraduate students from Villanova University who completed both the NEO-PI-3 (Costa & McCrae, 2010) and the PAI. As predicted, the internalizing dimension of the PAI was found to have a strong positive correlation with neuroticism, while the externalizing dimension was found to have strong negative correlations with agreeableness and conscientiousness. These results provide evidence of the construct validity for these dimensions of the PAI, and the use of the PAI as a unified measure of both internalizing and externalizing symptoms.