This thesis is a study of the origins and rationale of two categories of house museum - here named "Great Man" and "Social History" - in the United States and Australia. An examination of cultural, social and historical change provides the context for the genres' evolution. The Great Man genre was born in mid nineteenth-century America when two houses associated with George Washington - Hasbrouck House and Mount Vernon - were preserved and translated to museum status. Mount Vernon quickly became the exemplar for house museums. Civil religion, a secular nationalism that adopted the forms and rituals of church religion, focusing on hero worship, pilgrimage and contemplation of transcendent collective purpose, provided the ideology that sustained the new museum type. Great Man house museums became the shrines at which such rituals could be practiced. In the early twentieth-century the specialization of heritage organizations encouraged a new breed of heritage professional. Largely fabric focused, these "new museum men" influenced philosophy, management and conservation practice at house museums throughout the century. Social history made its impact upon house museums in the latter decades of the twentieth century. The paradigm encouraged the creation of a new category of house museum. Existing Great Man house museums adopted some of its characteristics though never lost their hero worship foundations. In fact, I posit that the idea of hero worship was transferred to the new genre. The birth and evolution of the two categories of house museum is demonstrated through four biographical studies: Vaucluse House in Sydney; Monticello in Charlottesville VA; the Lower East Side Tenement Museum in New York City; and Susannah Place Museum in Sydney. I believe the findings demonstrate an argument that applies at hundreds of house museums in the United States and Australia.