Mild cognitive impairment and mild dementia are common problems in the elderly. Primary care physicians are the first point of contact for most patients with these disorders and should be familiar with their diagnosis, prognosis, and management. Both mild cognitive impairment and mild dementia are characterized by objective evidence of cognitive impairment. The main distinctions between mild cognitive impairment and mild dementia are that in the latter, more than one cognitive domain is invariably involved and substantial interference with daily life is evident. The diagnosis of mild cognitive impairment and mild dementia is based mainly on the history and cognitive examination. The prognosis for mild cognitive impairment and mild dementia is an important motivation for diagnosis because in both, there is a heightened risk for further cognitive decline. The etiology of mild cognitive impairment and mild dementia can often be established through the clinical examination, although imaging and other laboratory tests may also contribute. Although Alzheimer disease is the most common cause of both, cerebrovascular disease and Lewy body disease make important contributions. Pharmacological treatments are of modest value in mild dementia due to Alzheimer disease, and there are no approved pharmacological treatments for mild cognitive impairment of any etiology. Nonetheless, new-onset cognitive impairment is a worrisome symptom to patients and families that demands answers and advice. If a patient is having difficulties managing medications, finances, or transportation independently, diagnosis and intervention are necessary to ensure the health and safety of the patient.