The authors of the "No Child Left Behind Act of 2001" anticipated that a majority of school districts or schools would not be able to attain state and national achievement standards without assistance. Consequently, the Act created a major tenet known as Supplemental Educational Services (SES) programs to improve the learning outcomes of students placed "at-risk" and to hold public schools accountable for increasing the proficiency levels of students in reading and mathematics. This study examined whether provision of supplemental educational services significantly improved academic achievement of students in Baltimore City Public Schools after they received supplemental services. A quasi-experimental research design was utilized in this study to compare SES participants and non-participants. (Contains 5 tables.)