Stroke is a leading cause of adult disability because of its physical and cognitive consequences. Cognitive changes are important contributors to family caregivers' experiences of emotional distress. To date, measures to assess cognition treat it as a global construct, but it is more likely that unique domains differentially affect family caregivers. The research objectives in this study were to: (1) identify the different domains of cognitive changes in the form of behavioral and psychological symptoms after stroke, and (2) establish the reliability of the Brain Impairment Behavior Scale (BIBS) in measuring cognitive domains. Family caregivers of stroke survivors (N = 300) completed the BIBS as part of cross‐sectional and longitudinal studies. A subsample of caregivers completed the BIBS twice, 2 weeks apart, to examine the scale's test‐retest reliability. We used exploratory factor analysis to identify four domains of behavioral and psychological symptoms in the BIBS: apathy, depression/emotional distress, comprehension/memory problems, and irritability. Internal consistency for the subscales representing each identified domain ranged from .78 to .91, and the 2‐week intra‐class correlation coefficients ranged from .75 to .88. Future research and clinical use of this measure will increase our understanding of how specific domains of stroke survivors' behavioral and psychological symptoms affect the well‐being of family caregivers.