Although the strong link between maternal education and children's outcomes is one of the most well-established findings in developmental psychology (Reardon, 2011; Sirin, 2005), less is known about how young, low-income children are influenced by their mothers completing additional education. In this research, longitudinal data from the Head Start Impact Study were used to explore the associations between increases in maternal education and Head Start eligible children's cognitive skills and behavioral problems in 1st grade. Propensity score weighting was used to identify a balanced comparison group of 1,362 children whose mothers did not increase their education between baseline (when children were aged 3 or 4) and children's kindergarten year, who are similar on numerous covariates to the 262 children whose mothers did increase their education. Propensity-score weighted regression analyses indicated that increases in maternal education were positively associated with children's standardized cognitive scores, but also with higher teacher-reported externalizing behavioral problems in 1st grade. The increases in externalizing behavioral problems were larger for children whose mothers had less than a college degree at baseline.