Policies and practices associated with intra-district teacher transfers in urban school districts were examined, exploring the implications for educational equity of this aspect of teacher mobility. Human capital theory and the theory of internal labor markets and their institutional rules provided the primary theoretical focus of the research. Four urban districts were included in the study, districts in distinct areas of the United States in which teacher union activity and strength varied considerably. Respondents were 11 school administrators (3 secondary and 8 elementary), 1 former principal, 5 school district officials, 3 local union representatives, a former college of education dean, 4 college of education professors, and an education specialist with the local government. Data provide evidence that the problem of teacher transfer is often more complex than the literature usually indicates. Seniority-based transfer of teachers away from low-income schools is typically associated with union contract provisions. Internal labor market rules in the Northeastern and Midwestern school districts are largely governed by union contracts, and transfer patterns in the Northeastern city generally operate as predicted by earlier teacher mobility studies. However, the process of teacher transfers in the two Southeastern cities operates in less expected ways. In the smaller district, teachers regularly move from low to higher socioeconomic status schools, even in the absence of contract provisions allowing seniority-based transfer. In the other district, an emphasis on desegregation and efforts to give consideration to schools with the greatest needs appear to have contributed to a decline in the rate of transfer. Transfers of quality teachers out and ineffective teachers in often interfere with efforts to offer meaningful staff development, build a sense of mission, and foster a collegial atmosphere among the staff. (Contains 49 references.) (SLD)