This chapter presents an overview of the theoretical law and economics literature on the burden of proof within tort law. I begin by clarifying core legal definitions within this topic, demonstrating that the burden of proof actually refers to at least five doctrinal concepts that substantially overlap but are not completely interchangeable. I then provide a conceptual roadmap for analyzing the major extant contributions to this topic within theoretical law and economics, emphasizing three key dimensions that organize them: (a) where they fall in the positive-normative spectrum; (b) what type of underlying modeling framework they employ (ranging from decision theoretic to game theoretic to mechanism design); and (c) whether they focus on litigation activity or primary activities (or both). In the aggregate, the resulting theoretical landscape is a complex one, yielding a number of interesting insights. Yet it still suffers from having no single unified theory. I conclude by offering a number of recommendations about where applied law and economics scholars interested this topic could direct their research efforts.