Regional, facility, and racial and ethnic variability in intensity of care provided to nursing home residents with advanced dementia is well documented but poorly understood. To assess the factors associated with facility and regional variation in the intensity of care for nursing home residents with advanced dementia. In the ADVANCE (Assessment of Disparities and Variation for Alzheimer Disease Nursing Home Care at End of Life) qualitative study, conducted from June 1, 2018, to July 31, 2021, nationwide 2016-2017 Medicare Minimum Data Set information identified 4 hospital referral regions (HRRs) with high (n = 2) and low (n = 2) intensity of care for patients with advanced dementia based on hospital transfer and tube-feeding rates. Within those HRRs, 14 facilities providing relatively high-intensity and low-intensity care were recruited. A total of 169 nursing home staff members were interviewed, including administrators, directors of nursing, nurses, certified nursing assistants, social workers, occupational therapists, speech-language pathologists, dieticians, medical clinicians, and chaplains. Data included 275 hours of observation, 169 staff interviews, and abstraction of public nursing home material (eg, websites). Framework analyses explored organizational factors and staff perceptions across HRRs and nursing homes in the following 4 domains: physical environment, care processes, decision-making processes, and implicit and explicit values. Among 169 staff members interviewed, 153 (90.5%) were women, the mean (SD) age was 47.6 (4.7) years, and 54 (32.0%) were Black. Tube-feeding rates ranged from 0% in 5 low-intensity facilities to 44.3% in 1 high-intensity facility, and hospital transfer rates ranged from 0 transfers per resident-year in 2 low-intensity facilities to 1.6 transfers per resident-year in 1 high-intensity facility. The proportion of Black residents in facilities ranged from 2.9% in 1 low-intensity facility to 71.6% in 1 high-intensity facility, and the proportion of Medicaid recipients ranged from 45.3% in 1 low-intensity facility to 81.3% in 1 high-intensity facility. Factors distinguishing facilities providing the lowest-intensity care from those providing the highest-intensity care facilities included more pleasant physical environment (eg, good repair and nonmalodorous), standardized advance care planning, greater staff engagement in shared decision-making, and staff implicit values unfavorable to tube feeding. Many staff perceptions were ubiquitous (eg, adequate staffing needs), with no distinct pattern across nursing homes or HRRs. Staff in all nursing homes expressed assumptions that proxies for Black residents were reluctant to engage in advance care planning and favored more aggressive care. Except in nursing homes providing the lowest-intensity care, many staff believed that feeding tubes prolonged life and had other clinical benefits. This study found that variability in the care of patients with advanced dementia may be reduced by addressing modifiable nursing home factors, including enhancing support for low-resource facilities, standardizing advance care planning, and educating staff about evidence-based care and shared decision-making. Given pervasive staff biases toward proxies of Black residents, achieving health equity for nursing home residents with advanced dementia must be the goal behind all efforts aimed at reducing disparities in their care.