Firm size, in and of itself, is hardly a "goal" of the regulators. Indeed, the growth of very large firms, and the increase in market concentration that accompanies it, will add to the debate over the adequacy of the regulator's management of the industry. It must be demonstrable that very large firms assist the regulators in attaining some of their espoused goals, goals that they might not attain otherwise. What have we learned? The evidence does not all point in one direction. On the question of whether large firms can deliver their services more efficiently than can small ones, our answer is that scale economies are not as easily demonstratable as others have concluded. Such economies turn out to be crucially dependent on the way in which they are specified in the cost function. An examination of the likely biases of each functional form suggests that only relatively small firms would experience real efficiency gains from growth. Large firms seem to be neither more nor less efficient than their smaller cousins, insofar as private costs reflect public costs. / Ph. D.