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Apathy, defined as a decrease in purposeful or goal-directed behavior, is common in many neurological disorders. The assessment of apathy in these disorders is important as apathy is associated with differential engagement and response to treatment and future cognitive and functional decline. Although apathy is often described as including three separate symptom dimensions, reflecting diminished interest, action, and emotional expression, investigations of the factor structure of apathy symptoms have been limited by the use of scales which do not comprehensively assess all of three of the proposed dimensions. The current study aimed to develop a novel informant report measure of apathy symptoms, investigate the factor structure of apathy symptoms, and examine the relationship of different types of apathy symptoms to several clinically relevant variables. Participants included 249 informants who reported on an individual with (n=210) or without (n=39) a neurological or psychiatric condition. Results showed the best fitting model of apathy symptoms was a bifactor model in which apathy could be represented as a global dimension with three separate, specific symptom factors reflecting diminished interest and initiative, asociality, and diminished emotional and verbal expression. In general, apathy was associated with poorer cognitive functioning, greater functional impairment, and higher caregiver distress. The specific symptom factors differed somewhat in their association with those same variables, highlighting the utility of measuring different types of symptoms in addition to overall apathy. Future work will refine the apathy measure developed in this study and test the obtained bifactor symptom model in an independent sample.