Key PointsQuestionIs implementation of a mandatory managed long-term care (MLTC) program associated with changes in nursing home use among older adults with dementia?FindingsIn this cohort study of 463 947 Medicare beneficiaries with dementia, implementation of mandatory Medicaid MLTC in New York State between 2012 and 2015 was associated with a decrease in nursing home use among dual enrollees 65 years and older with dementia.MeaningThese findings suggest that mandatory MLTC may help to prevent or delay nursing home placement among older adults with dementia.