The assessment of complex interventions is defined by the need to make difficult trade-offs: time, money, talent and support always seem inadequate. But such pressures only intensify the need for good theory, breadth of experience, depth of commitment to professional standards, and giving stakeholders a reasoned basis on which to act. The strategies and cases outlined in this insightful book demonstrate how this can be realized in practice. The Qualitative Impact Protocol enables applied social science to do its job: to faithfully uphold accountability norms while generating sound and usable conclusions