This article provides a conceptual framework for understanding what is involved in improving urban science teaching and what might be implied by conducting research on its improvement. It is argued in this article that three sets of forces and conditions have a direct impact on urban science classrooms: first, the array of interdependent policies at school, district, and state levels about science teaching in particular and about education improvement more broadly construed; next, the investment and use of instructionally relevant resources at each of the three levels and their differing impacts on the renewal of urban science teaching; and finally, the broader context in which urban science teaching occurs mediating how these resources are—or can be—used. Mediating factors include the professional peer community, subject-specific instructional leadership, the professional development infrastructure, the supply of available science teachers, and the broader community context. The article concludes with suggestions for how this framework informs directions for future research on the promise and limits of efforts to renew science teaching in urban settings. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 1089–1100, 2001