All academic disciplines periodically appraise their effectiveness, evaluating the progress of previous scholarship and judging which approaches are useful and which are not. Although no field could survive if it did nothing but appraise its progress, occasional appraisals are important and if done well can help advance the field.This book investigates how international relations theorists can better equip themselves to determine the state of scholarly work in their field. It takes as its starting point Imre Lakatos's influential theory of scientific change, and in particular his methodology of scientific research programs (MSRP). It uses MSRP to organize its analysis of major research programs over the last several decades and uses MSRP's criteria for theoretical progress to evaluate these programs. The contributors appraise the progress of institutional theory, varieties of realist and liberal theory, operational code analysis, and other research programs in international relations. Their analyses reveal the strengths and limits of Lakatosian criteria and the need for metatheoretical metrics for evaluating scientific progress.