The representative firm has been a much-criticized concept, subject to conflicting interpretations with respect to both its configuration and its intended role in Marshall's Principles (the Principles).2 The concept found itself a focal point of much of the debate during the significant cost controversies of the 1920s; however, it has appeared infrequently in subsequent economic analysis.3 In its place, the equilibrium firm has taken centre stage in the microeconomic textbooks, sometimes being mistaken for its vanquished predecessor. It is argued in this chapter that an evaluation of the role of Marshall's representative firm must proceed within the context of its intended purpose. It is contended that Marshall's representative firm was ver...