This book explores American medical relief to Spain and China in the 1930s and 1940s as responses to the Spanish Civil War and the Second Sino-Japanese War. Although serving vastly different peoples in strikingly distant landscapes, the three aid organizations focused on here illustrate a transition in how Americans responded to foreign conflict and how humanitarian aid was used as a political tool. The story of these small and relatively unknown organizations can help refine historical understanding of the development of humanitarianism and the evolution of global citizenship in the twentieth century.