This article examines the effects of early life socioeconomic conditions on the risk of cognitive impairment among oldest old persons in China. We also examine whether adult socioeconomic status mediates the association between early life socioeconomic status and cognitive impairment in old age. Data derived from two waves (1998-2000) of the Chinese Longitudinal Healthy Longevity Survey. We estimated logistic and multinomial regression models of cognitive impairment for a nationwide sample of people aged 80 to 105 (N = 8,444). Among both men and women, urban residence in early life as well as education was associated with lower odds of cognitive impairment at baseline. We found modest support for a protective effect of advantaged childhood background on the odds of cognitive impairment onset during the 2-year follow-up, especially among women. Our findings suggest that socioeconomic environment throughout the life course, early life in particular, can influence the risk of cognitive impairment in old age. Not only can public policy that targets illiteracy, hunger, and poverty improve the lives of tens of thousands of children, but ultimately such investments will pay significant dividends many decades later in enhancing the cognitive well-being of older persons.