The theory of monopoly price was originally formulated by Carl Menger at the inception of the marginalist revolution in 1871 and represented the dominant theoretical approach to monopoly until the 1930s. Despite its impeccable doctrinal pedigree and lengthy dominance, the theory abruptly disappeared from the mainstream neoclassical literature after the Monopolistic Competition Revolution, to be revived and reformulated after World War II by Ludwig von Mises. The present paper describes the theory as it was offered in its most sophisticated pre‐war form by American economist Vernon A. Mund, who published an unjustifiably neglected volume on monopoly theory that appeared in the same year as the classic works by Joan Robinson and Edward Chamberlain. This paper then attempts to draw out the critical implications of Mund’s formulation of the theory for the current neoclassical orthodoxy in monopoly and competition theory, including the elasticity of demand curves facing individual producers under competition, the time perspectives that are most relevant in analyzing the pricing process, the proper role of long‐run equilibrium in this analysis, and the misapplication of the marginal revenue and marginal cost concepts. Finally, the paper suggests a number of reasons why the theory was swept aside in the aftermath of the Chamberlain/Robinson Revolution with almost no resistance from its most prominent exponents.