The current study applies Cumulative Inequality theory to investigate whether differences in black, white, and Hispanics mothers’ early life socioeconomic status (SES) account for disparities in infants’ risk of low birthweight (LBW). This study uses three-generation linked data that come from the National Longitudinal Survey of Youth 1979 (1979-1995) and the NLSY Young Adult sample (1994-2010) and contain information on the mothers and grandmothers of 2,332 singleton infants. Controlling for mothers’ health and adult SES, I assess the unique association between childhood low SES, in terms of both cumulative economic hardship (i.e., household poverty status from ages 0 to 14) and social status (i.e., grandmothers’ education and marital status), and LBW probability. I also examine differences in LBW probability between black, white, and Hispanic women from similar childhood socioeconomic backgrounds. Overall, results indicate that childhood socioeconomic factors do not account for race/ethnic disparities in LBW. Rather, childhood low SES increases the probability of LBW for whites but is not significantly predictive of LBW for blacks or Hispanics. In fact, pairwise comparisons indicate the greatest LBW disparities exist between black and white women who experienced the least socioeconomic disadvantage during early life.