This dissertation examines legal and social actions and beliefs regarding mixed race and interracial marriage and relationships in the Deep South from Reconstruction through the end of Jim Crow. Using court cases dealing with miscegenation and racial identity, it examines the contrast between the ways that laws defined and regulated race and the ways that local communities dealt with the same issues. While miscegenation and racial definition laws became stricter and encompassed more people throughout the nineteenth and twentieth centuries, ultimately moving toward a one-drop standard, in part because of the influence of the eugenics movement, courts struggled to apply these new definitions to actual situations because of persistent racial ambiguity. Furthermore, evidence from court cases indicates that communities, in contravention of the law, often continued to define race based on appearance and reputation rather than "scientific"? assessments of blood, as well as to tolerate infractions against legal Jim Crow, including miscegenation. Thus, while increasingly strict legal restrictions were intended to maintain tight control over race and racial behavior in the South, they often failed to achieve this level of control on a local or individual level, largely because of this ongoing community toleration as well as the persistent inability to apply racial definitions in real life situations. Rather than a monolithic legal and social system buttressed by a common understanding of what race meant, then, the Jim Crow period encompassed a wide variety of opinions, motivations, and actions regarding race.