1. Using case studies to enhance the quality of explanation and implementation: integrating scholarship and development practice Jennifer Widner, Michael Woolcock, and Daniel Ortega Nieto; Part I. Internal and External Validity Issues in Case Study Research: 2. How to learn about causes in the single case Nancy Cartwright; 3. RCTs versus observational research: assessing the trade-offs Christopher Achen; 4. Drawing contingent generalizations from case studies Andrew Bennett; 5. Will it work here? Using case studies to generate 'key facts' about complex development programs Michael Woolcock; Part II. Ensuring High-Quality Case Studies: 6. Descriptive accuracy in interview-based case studies Jennifer Widner; 7. Selecting cases for comparative sequential analysis: novel uses for old methods Tommaso Pavone; 8. The transparency revolution in qualitative social science: implications for policy analysis Andrew Moravcsik; Part III. Putting Case Studies to Work: Applications to Development Practice: 9. Process Tracing for Program Evaluation Andrew Bennett; 10. Positive Deviance Cases: Their Value for Development Research, Policy, and Practice Melani Cammett; 11. Analytic Narratives and Case Studies; 12. Using Case Studies for Organizational Learning in Development Agencies Sarah Glavey, Oliver Haas, Claudio Santibanez, and Michael Woolcock; 13. Connecting Case Studies to Policy and Practice: Practical Lessons from Operational Experience Maria Gonzalez de Asis and Jennifer Widner.