An early adopter of public preschool (i.e., pre-kindergarten, "pre-k"), evidence from Baltimore City, Maryland, can provide insight for those working to improve access to early education opportunities. We followed a cohort of children entering kindergarten in Baltimore City Public Schools during the 2007-2008 year through the 2010–2011 academic year. Students were grouped by pre-k experience: public pre-k (n = 2828), Head Start (n = 839), Head Start plus public pre-k (n = 247), private pre-k (n = 993), or informal care (n = 975). After adjusting for individual- and school-level characteristics, students from the Head Start plus public pre-k group were the most likely to enter kindergarten with the foundational skills and behaviors needed to be successful (vs. all groups, P ? .001). Students in informal care were the least likely to enter kindergarten with this skillset (vs. all pre-k groups P ? .001). Children from informal care were also significantly more likely than all other groups to be chronically absent in kindergarten (P ? .001). By third grade, children from informal care were least likely to be reading on grade level and most likely to have been retained a grade (vs. all pre-k groups P ? .001). Children from disadvantaged populations who were not enrolled in pre-k faced significant difficulties keeping up with their peers throughout elementary school; interventions to improve their transition to school and increase their likelihood of academic success are warranted. Universal preschool is likely to improve education outcomes for children in urban areas. (author abstract)