David Spafford examines the relationship between warrior houses and their names in fifteenth- and sixteenth-century Japan. Widespread reliance on adoption of heirs and the less common revivals of extinct houses reveal how late medieval warriors framed the membership and boundaries of the house (ie). Together and separately, adoptions and revivals force us to reckon with the malleable nature of warrior houses—which included both kin and non-kin—and their essentially political character. They force us to think through the several dimensions of the ie as an analytical framework: heraldic group, house/lineage, household. The decisions of individuals and individual lineages about naming, affiliation, and identity demonstrate both that a house’s surname served to symbolize familial continuity and that the openly constructed nature of the house-as-multigenerational-named-entity allowed strategic use of marriage and adoption for family survival through the long age of civil strife.