A dynamic game model of production and capital investment choice is formulated and used to explain the behavior of leading firms in the post-war American aluminum industry. A dominant firm equilibrium simulation is found to predict behavior of leading firms better than a Nash equilibrium. The model performs well in its prediction of average real prices in the post-war period. The model explains some, but not all, of the observed excess production capacity that arises. The remedy following Alcoa's monopolization conviction in 1945 is examined. Industry simulations involving a more competitive post-war market structure predict a small welfare gain.