Universal educational policies are a popular tool to address inequalities in educational achievement.  These policies may be ineffective, and may actually exacerbate inequality, if families of high socioeconomic status are better able to advocate for their children, make informed decisions, or circumvent policy to their child’s benefit. We examine whether a statewide policy enacted in Florida in 2002, mandating that promotion to the fourth grade be conditional upon meeting a minimum standard of reading, resulted in differential retention and later achievement dependent on mothers’ level of education.  Because the Florida policy relies on a strict score cutoff for determining retention, we employ a regression-discontinuity design to look at differences in the implementation and effect of the policy for the marginal student.  We find that among students within the same school during the same year, students who score just below the cutoff for promotion are much less likely to be granted an exemption from the retention policy if they have a less educated mother. Scoring below the promotion cutoff results in an increase in retention probability that is 20 percent larger for students whose mothers have less than a high school degree than for students whose mothers have a bachelor’s degree or more. We do not find any evidence that students are differentially impacted by the policy dependent on maternal education.  Short term achievement gains were found for all students which faded to insignificance after four years.