Deep-seated antagonisms exist between qualitative and quantitative researchers. These tensions derive from differences in goals and epistemologies. The purpose of this volume of New Directions for Program Evaluation is to examine the nature of these differences, their origins, and their consequences. The contributors ask whether rapprochement is possible and, if so, how the relationship between qualitative and quantitative inquiries might be structured so that we can be enriched rather than diminished by our diversity. The authors well represent both the qualitative and quantitative perspectives. But they are not partisans defending ideological turfs; they are only individuals trying to come to grips with the challenges that program evaluation faces because of a diversity of principles and practices.