This study of teacher staffing issues in the School District of Philadelphia explores the degree to which the district has succeeded in upgrading teachers' professional credentials, recruiting and retaining them, and equitably distributing experienced and credentialed teachers across all types of schools. Since the passage of "No Child Left Behind" (NCLB) and the state's takeover of the district in 2001, the district has succeeded in improving the certification rates of its teachers, especially new teachers, and in drastically cutting the number of emergency-certified teachers and classroom vacancies. It has also improved new teacher retention and has modernized and decentralized its hiring process. It has not, however, been able to change the pattern of having the least qualified teachers in schools serving the highest percentages of poor and minority students nor its poor long-term rate of teacher retention. The study also notes that measures taken to comply with NCLB deadlines have strengthened the district's relationships with the Philadelphia Federation of Teachers (PFT), local higher education outlets, and alternate certification partners. The authors' research on the teacher workforce issue is one strand of a larger study, "Learning from Philadelphia's School Reform," a research and public awareness project led by Research for Action that is assessing the effectiveness of school improvement in Philadelphia. The following are appended: (1) Data and Methods; and (2) Alternate Route Certification Programs in the School District of Philadelphia. (Contains 65 endnotes, 8 tables, and 8 figures.)