Cognitive impairment, Alzheimer’s disease, and other dementias are important health concerns for older adults. As a marginalized and growing segment of the older adult population, lesbian, gay, bisexual, and transgender (LGBT) older adults face distinct risk factors related to cognitive impairment and dementias, including social isolation, discrimination, barriers to health care access, limited availability of and support for caregivers, and higher rates of certain chronic illnesses. We examine cognitive impairment and dementias among LGBT older adults, describe their unique risk factors, and outline key competencies for health care and human service providers to ensure culturally relevant care for LGBT older adults experiencing cognitive impairment, Alzheimer’s disease, or other dementias, as well as their caregivers, families, and communities. Implications include developing an awareness of the context of LGBT older adults’ lives and relationships, the importance of early detection and support, and the development of policies and practices that promote community-level advocacy and education.