Identification of persons at risk for developing dementia is of increasing importance as the proportion of persons over the age of 65 years grows globally. This review examines the neuropsychological literature specifically addressing the concept of impaired cognitive functioning of insufficient magnitude to warrant a diagnosis of dementia and its meaning with respect to the development of dementia. Although the most obvious finding in the literature is that persons with impaired cognitive functioning have varied outcomes, it is clear that a significant proportion of persons with mild cognitive impairment progress to dementia over a 1- to 2-year interval and approximately 50% progress to dementia by 5 years. The best and most commonly identified predictors of decline to dementia include age and lower baseline performance on neuropsychological measures (e.g., measures of memory). In discussing these findings, issues related to sample definition, sample selection, and methodology are identified and recommendations for future research are provided.