This study estimates the prevalence of cognitive impairment without dementia (CIND) in the United States and examines its longitudinal outcomes. The Aging, Demographics, and Memory Study (ADAMS) is a nationally representative sample of individuals aged 71 years or older, with 856 participants completing initial assessments and 180 completing follow-up assessments. CIND was diagnosed using neuropsychological testing, neurologic examination, and clinical and medical history. National prevalence rates were estimated using population-weighted samples. In 2002, an estimated 5.4 million people (22.2%) aged 71 years or older had CIND, with prominent subtypes including prodromal Alzheimer disease (8.2%) and cerebrovascular disease (5.7%). Among those with CIND, 11.7% progressed to dementia annually, compared to 17% to 20% for subtypes of prodromal Alzheimer disease and stroke. The annual death rate was 8% for those with CIND and nearly 15% for those with CIND due to medical conditions. The study highlights the significant prevalence and heterogeneity of CIND, emphasizing the need for accurate national estimates to inform societal impact and public health strategies.This study estimates the prevalence of cognitive impairment without dementia (CIND) in the United States and examines its longitudinal outcomes. The Aging, Demographics, and Memory Study (ADAMS) is a nationally representative sample of individuals aged 71 years or older, with 856 participants completing initial assessments and 180 completing follow-up assessments. CIND was diagnosed using neuropsychological testing, neurologic examination, and clinical and medical history. National prevalence rates were estimated using population-weighted samples. In 2002, an estimated 5.4 million people (22.2%) aged 71 years or older had CIND, with prominent subtypes including prodromal Alzheimer disease (8.2%) and cerebrovascular disease (5.7%). Among those with CIND, 11.7% progressed to dementia annually, compared to 17% to 20% for subtypes of prodromal Alzheimer disease and stroke. The annual death rate was 8% for those with CIND and nearly 15% for those with CIND due to medical conditions. The study highlights the significant prevalence and heterogeneity of CIND, emphasizing the need for accurate national estimates to inform societal impact and public health strategies.