Global health interventions aim to improve health in communities. Underlying each intervention is a theory of change that addresses a specific constraint--such as poverty, limited access to clinical care, or weak governance--within the complex system that shapes global health. Theories of change can help explain broad global improvements such as those in life expectancy and child mortality. They can also be used to develop interventions for communities facing serious health problems. As global health problems are complex, different definitions of underlying constraints are often championed by different disciplines. Economists generally favor approaches that address poverty or economic instability; physicians advocate for improved health systems; engineers favor investment in technology; charities emphasize the importance of aid. However, monodisciplinary approaches ignore the complex systems that generate global health problems and omit a consideration of the strengths and weaknesses of potential interventions. In Theories of Change in Global Health, Stephen Luby and Sabina Faiz Rashid critically evaluate fifteen common theories of change that underlay global health interventions. Through case studies and examples of interventions across contexts, Luby and Rashid develop a framework of the conditions under which different theories of change have been successful and the conditions which predispose a particular theory of change to failure. As they argue, no single theory of change is a panacea. By spotlighting the often-implicit theory of change and underlying problem definition, this book aims to improve the specificity, depth, and effectiveness of interdisciplinary conversations around optimal strategies towards global health improvement. It also provides critical guidance about which theories of change are most promising and encourages stakeholders to broaden the range of possible interventions under consideration.