Background/Context: This article addresses which school-level factors contribute to school quality. Previous research has focused on assessing the effects of school-level variables on student-level quality (e.g., achievement). However, the field has been limited in not evaluating the effects of school-level factors directly on measured school-level quality. This present study takes this next step. Purpose/Objective/Research Question/Focus of the Study: The purpose of this study is to determine which school-level factors across three categories--schoolwide programs, school-level personnel, and institutional environment--are significant predictors of school quality. Population/Participants/Subjects: Two data sets from the School District of Philadelphia are employed. The first data set is longitudinal and comprises elementary school student data linked to teachers, classrooms, and neighborhoods. The second data set, linked to the first by way of school and year data, is longitudinal and comprises school-level variables for all elementary schools within the district over 3 years. Research Design: This investigation first derives four quantifiable measures of school quality based on the student- and classroom-level data set. These measures are based on student reading achievement scores, math achievement scores, yearly attendance, and behavior grades. In the main analyses, this study separately tests each measure of quality in an empirical model that relates school-level inputs to school-level outputs. Each model does so while holding constant student, teacher, classroom, and neighborhood covariates as well as principal and school budget data. Findings: Looking across all four measures of school quality, the study finds school quality to be higher in schools with music and language programs, more disciplinary resources per student with a behavior problem and more special education resources per special education student, having a school nurse, being a smaller sized campus, and being K-5 (versus K-8). Although there is some consistency in the predictors of school quality, this research also indicates that differentiating between all four measures of quality is critical: School-level factors provide distinct outcomes depending on the measure of school quality itself. Conclusions: By identifying those school-level factors that directly relate school quality to its programs, personnel, and environment, this study has differentiated between the particular institutional resources of urban elementary schools that can potentially influence schooling experiences, above and beyond student or classroom factors. As such, this study can be used to more effectively identify those significant institutional challenges faced by urban schools, how these challenges are actualized, and, moreover, the types and levels of resources necessary to enhance school quality.