In 2002, Congress reauthorized the Elementary and Secondary Education Act (1965), more commonly known today as the No Child Left Behind Act (2002). Many of the initiatives within the act have come under significant scrutiny, not least of which is providing supplemental educational services to students in "failing" schools. The purpose of this multi-site, cross-case study was to examine how supplemental educational services impact students as viewed through the perspectives of elementary school teachers and principals. Elementary school teachers and their principals who currently have, or have had in the recent past, students enrolled in these supplemental services were the targeted populations for this study. Teachers and principals were selected because they have unique and enduring interactions with students and are in a position to assess how programs such as those delivered by supplemental educational service providers affect students. Four schools were selected based on geographic location (reasonable proximity to the researcher), number of participants in supplemental educational services, NCLB designation (the school was designated as in the second year or beyond of improvement), and willingness to participate in the study. When data from the four schools were considered in a cross-case analysis, the following themes emerged: (1) students realized varying outcomes as a result of participating in supplemental educational services, (2) supplemental educational services varied in their perceived quality depending on whether the providers were internal or external, (3) teachers and principals considered communication with supplemental educational service providers as an indicator of their quality, (4) teachers and principals viewed tailoring of supplemental educational services to meet particular student's needs as a hallmark of their quality, (5) teachers and principals recommended using existing school assessments, observation, and attendance as measures of the impact of supplemental educational services, and (6) teachers and principals recommended increased communication, increased individualization of tutoring, certification of tutors, and changes in tutoring schedules as ways to improve supplemental educational services. These results provide policy makers with information that may be helpful in better understanding the impact of supplementary educational services on elementary students and how they might adjust the program to make it more effective. / Ph. D.