Dr Thomas Hodgkin was a physician and medical researcher as well as a humanitarian campaigner. Hodgkin’s science was informed by his social conscience and his affiliation to the Society of Friends, while his philanthropy rested on the presentation of systematically organized and scientifically derived evidence. This chapter discusses Hodgkin’s medical research and career, and then his significant contribution to the emerging disciplines of ethnology and geography. Hodgkin and his peers within newly emerging scientific disciplines established and used scientific societies to not only stake disciplinary claims, but also promote political and humanitarian objects. Exploring the myriad overlaps in personnel, ideas and approach between the different areas and organizations with which Hodgkin was involved, this chapter addresses the underappreciated connection between science and humanitarian activity in mid-century London, and the impact of that relationship on our reading of indigenous protection.